Dissertations / Theses: 'Luminescent Solar Concentrators'

1

Green, Adam. "Optical properties of luminescent solar concentrators." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/8361/.

Full text

Abstract:

This thesis on luminescent solar concentrators (LSC) presents work carried out as part of the Electronic and Photonic Molecular Materials (EPMM) group of the department of physics and astronomy at the University of Sheffield. The work is presented in five experimental chapters looking at a range of research aspects from film deposition and measurement instrumentation, to exploring LSC optical properties and device performances by spectral based analytical methods. A Gauge R & R (GRR) study design is used to assess sources of variance in an absolute fluorescence quantum yield measurement system involving an integration sphere. The GRR statistics yield the total variance split into three proportions; equipment, day-to-day and manufacturing variances. The manufacturing variance, describing sample fabrication, was found to exhibit the smallest contribution to measurement uncertainty. The greatest source of variance was found to be from fluctuations in the laser intensity whose uncertainty is carried into the quantum yield determination due to not knowing the exact laser intensity at the time of measurement. The solvation phenomenon is explored as a potential way to improve LSC device yields; this occurs due to excitation induced changes to a fluorophore's dipole moment which leads to a response by the surrounding host medium resulting in shifts in fluorophore emission energy. This effect is shown to improve self-absorption efficiency by reducing the overlap of absorption and emission for particular organic fluorophores. This is expected to greatly improve energy yields but current dopant materials are too costly to employ according to the cost evaluations of this thesis. A spray coating deposition tool is considered for the deposition of thin film coatings for bi-layer LSC devices. A screening study design of experiment is constructed to ascertain the level of control and assess the tool's ability to meet thin film requirements. Despite poor control over the roughness of the thin film layer this property was found to lie close to the acceptable roughness limit in most samples. The biggest issue remains the film thickness achieved by the deposition, which was an order of magnitude too small according to Beer-Lambert absorption models. This spray-coating tool is thus unsuitable for the requirements of a bi-layer LSC. Concentration quenching is explored in the context of LSC device efficiency. Different fluorophores are seen to exhibited varied quenching decay strengths by looking at quantum yield versus fluorophore concentration. For two fluorophores, 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) and 2,3,6,7-Tetrahydro-9-methyl-1H,5H-quinolizino(9,1-gh)coumarin (C102), the quenching process is explored further using quantum yield and lifetime measurements to extract the quenching rate from rate equations. The form of the quenching rate as a function of molecular separation is shown to be of a monomial power law but distinct from the point-like dipole-dipole coupling of Förster resonant energy transfer (FRET). Additional quenching modes including surface-point and surface-surface interactions are considered to explain the power law form. Spectral analytical models have been constructed to model performance metrics for square-planar LSC devices. In this model the input solar irradiance is considered to be incident normal to the LSC collection face. Device thickness optimisation is explored to ensure maximisation of the absorption efficiency by the fluorophore using Beer-Lambert absorption modelling. The normalised fluorophore emission spectrum is converted to an equivalent irradiant intensity spectrum based on the amount of energy absorbed. Propagation of this energy through the LSC structure is considered in terms of the mean path length of light rays waveguided by total internal reflection and again Beer-Lambert absorption modelling. Self-absorption and host transport losses are included in some detail. Out-coupling of LSC irradiance at the harvesting edges to connected solar cells is then modelled, using c:Si and GaAs power conversion efficiency spectra, and the resultant power output performance can therefore be estimated. Comparison with real devices from literature show that the model works reasonably well compared to these single device configurations and is somewhat conservative in its estimates. Cost efficiency models based on reasonable assumptions conclude the scope of this work showing that current materials fall short of delivering competitive energy solutions by at least factor of 2 in the case of the best dye modelled here.

APA, Harvard, Vancouver, ISO, and other styles

2

Farrell, Daniel James. "Characterising the performance of luminescent solar concentrators." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506109.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Fisher, Martyn. "Optimization and novel applications of luminescent solar concentrators." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/24691.

Full text

Abstract:

The luminescent solar concentrator (LSC) was first proposed in the 1970s as a means to reduce the high cost of generating solar energy. The basic design was simple: a large transparent plate doped with an appropriate luminescent material which is able to absorb both direct and diffuse sunlight, and then guide photons produced by photoluminescence to its narrow edges where they are converted by photovoltaic cells. Unfortunately, the LSC has suffered from numerous efficiency losses and short lifetimes. Therefore, new luminescent species and novel approaches are needed for its practical application. Novel luminescent species studied in this thesis include arrays of vertical, self-aligned CdSe/CdS nanorods. The nanorods emit preferentially in the waveguiding plane and were characterised to ascertain the extent of self-alignment, and to determine their viability and this alignment technique for LSCs. Furthermore, a number of generations of bio-derived Phycobillisomes, a light absorbing pigment found in species of red algae, have been also been investigated and are a possible source of cheap and abundant luminescent material. Lastly, several luminescent species consisting of metal complexes and oligomers with high Stokes-shift were investigated. High Stokes-shift materials are essential if LSC efficiencies are to be increased as they mitigate the re-absorption that generally constitutes the dominant loss mechanism. This thesis features two novel LSC applications. The first is a large area, flexible LSC system for portable power generation. Computational raytrace simulations reveal the device is feasible but will require high Stokes-shift materials. The second novel approach utilises a tandem LSC system in conjunction with a photoelectrochemical cell (PEC). In the tandem design the upper concentrator provides blue light to excite a Fe2O3 photoanode for water oxidation while the lower concentrator provides red light that is converted by Si cells producing sufficient voltage to enable hydrogen production at a Pt electrode contained within the PEC.

APA, Harvard, Vancouver, ISO, and other styles

4

Raeisossadati, Mohammadjavad. "Luminescent solar concentrators to increase microalgal biomass productivity." Thesis, Raeisossadati, Mohammadjavad (2020) Luminescent solar concentrators to increase microalgal biomass productivity. PhD thesis, Murdoch University, 2020. https://researchrepository.murdoch.edu.au/id/eprint/55549/.

Full text

Abstract:

Light is the main limiting factor of any mass microalgal cultivation resulting in relatively low biomass productivity in raceway ponds. Microalgal cells in open ponds are normally photoinhibited on the surface and photolimited at the depth of the cultures where there is total darkness. Delivering light to the microalgal cells at the depth of cultures in large scale raceway ponds can increase biomass productivity. Luminescent solar concentrators (LSCs) can potentially be an economical light-diffusing system to be used in algal biotechnology. The main advantage of luminescent solar concentrators is that a solar tracking system is not needed. This results in less cost compared to other diffusing systems. Luminescent particles such as organic dyes or quantum dots (QDs) are the main constituents of LSCs. Luminescent particles absorb photons when light hits the surface of LSCs and the absorbed light is reflected internally and emitted from the edges at a longer wavelength. To the best of my knowledge, to date, there have been no attempts in using LSCs as a light guide for the growth of microalgae in any open system. Thus, the main aim of this study was to evaluate the effect of LSCs as a light guide to deliver light to the depth of microalgal cultures in raceway ponds to increase both biomass and high-value productivities. To assess the viability and efficacy of the LSCs system in an algal raceway pond, it is first necessary to select the most suitable microalgae species for this purpose. Three species, Arthrospira platensis (MUR 129), Scenedesmus sp. (MUR 268) and Chlorella sp. (MUR 269). were chosen for a laboratory experiment to investigate the effect of red and blue LSCs on the productivity of cultures. Arthrospira platensis showed up to 9% higher productivity when red LSCs were used compared to control and blue LSCs. The biomass productivity of Scenedesmus sp. cultures under red LSCs was also 30% and 4.5% higher compared to that in control and blue LSCs. The growth rate of Chlorella sp. cultures did not improve under red and blue LSCs. Furthermore, Scenedesmus sp. culture resulted in 30% higher cell density in cultures with red LSCs compared to that in control. Thus, Arthrospira platensis and Scenedesmus sp. were chosen as the most suitable species for further outdoor investigations using micro raceway ponds. In the next stage, Arthrospira platensis and Scenedesmus sp., were grown using red and blue LSCs and compared with control cultures with no LSCs using micro raceway ponds (0.1 m2) with the final culture volume of 21.5 L. The LSCs were installed on the edge of raceway ponds to have 200 mm of a panel inside the raceway pond and 100 mm of the panel out of the pond facing the sun to collect visible and diffuse light from sunlight, downgrade and, transfer it to the depth of A. platensis cultures. The bottom part of LSCs inside the A. platensis culture was also laser-cut to have enough surface area to increase the irradiance. Arthrospira platensis cultures when grown with red LSCs, reached a significantly higher biomass yield (1.77 ± 0.014 g L−1) compared to control (1.53 ± 0.002 g L−1) and blue LSCs (1.59 ± 0.056 g L−1). The biomass productivity of 57 ± 3.2 mg L−1 d−1 (12.2 g m−2 d−1) was obtained when Arthrospira cultures in raceway ponds were equipped with red LSCs. This was 24% and 26% higher than the biomass productivity of Arthrospira cultures when grown in raceway ponds with blue LSCs and control. There was no significant difference between the productivity of Arthrospira cultures with blue LSCs and control. Furthermore, the maximum phycocyanin productivity in Arthrospira cultures with red LSCs was 8.49 ± 0.9 mg L−1 d−1, which was 14% and 44% higher than that in cultures with blue LSCs and control cultures. In addition, the phycocyanin content of A. platensis was 136 mg L−1 (77 mg gbiomass−1) and 141 mg L−1 (89 mg gbiomass−1) under red and blue LSCs, respectively. The results of showed that red LSCs can significantly increase Arthrospira’s growth and productivity. Based on the outcome of this study, only red LSCs were applied to outdoor Scenedesmus sp. cultures in the next experiment. When grown with red LSCs, Scenedesmus sp. cultures reached a higher cell density compared to the control. Furthermore, the maximum specific growth rate (µ) of Scenedesmus sp. cultures with red LSCs was 16% higher than control with no LSCs. The biomass productivity of 43.6 ± 1.3 mg L-1 d-1 (9.4 g m-2 d-1) was obtained for Scenedesmus sp. cultures equipped with red LSCs which was 18.5% higher than that for Scenedesmus sp. cultures when grown in raceway ponds with no LSCs. Further, the protein content of Scenedesmus sp. under red LSCs was 436 mg gbiomass-1 (43.6%) which was 17.5% higher than that in control. The lipid content of Scenedesmus cultures under red LSCs (133 mg gbiomass-1) was also 10% higher compared to control with no LSCs. However, the carbohydrate content of Scenedesmus sp. cultures with red LSCs and control was not significantly different. The results of all indoor and outdoor experiments showed that using red LSCs on Arthrospira platensis and Scenedesmus sp. cultures was promising. More light availability to microalgal cells into the depth of the cultures is the most likely reason for having higher productivity in cultures with red LSCs. From the energy perspective, the results showed that the total amount of photosynthetic active radiation (PAR) available for A. platensis and Scenedesmus sp. cells at the depth of each pond emitting from four red LSCs is 34 µmol photons s−1. In other words, using red LSCs in each outdoor raceway pond bring about 34 µmol photons s−1 more light to the depth of A. platensis and Scenedesmus sp. cultures. This means injecting 34 µmol photons s−1 deep into the A. platensis and Scenedesmus sp. cultures where it would otherwise be in full darkness. This helps move the light from the photosaturated surface to the depth of the microalgal cultures. Moreover, based on the mixing rate, the thickness of the LSCs and surfaces of each red LSC, A. platensis and Scenedesmus sp. cells received brief bursts of light when they pass an edge and a surface of LSCs. For instance, considering PAR emitting from an edge of a red LSC (110 Wm−2/506 µmol photons m−2 s−1), A. platensis and Scenedesmus sp. cells received around 506 µmol photons m−2s−1 in 27 ms from each edge and 276 µmol photons m−2 s−1 in 218 ms when they pass each surface of a red LSC. In other words, it can be said that A. platensis and Scenedesmus sp. cells with red LSCs received brief bursts of light with different intensities for durations less than a second inside the cultures while there was total darkness for the cultures without LSCs. Finally, the costs of biomass and phycocyanin production using luminescent solar concentrators as a light delivering system on an industrial scale raceway pond cultivation of Arthrospira was assessed. The results showed that using red luminescent solar concentrators would result in a biomass and phycocyanin production costs of AU$ 3.16 and AU$ 125 per kg, respectively, which are 14% and 35% lower than the corresponding costs in a conventional raceway pond with no LSCs. The biomass and phycocyanin production costs of Arthrospira cultivation in conventional raceway ponds (with no LSCs) were AU$ 3.67 and AU$ 187 per kg, respectively. These results showed that using LSCs for growing Arthrospira can significantly lower the cost of biomass and phycocyanin production if the same size production facility is used. In conclusion, this study clearly showed that using LSCs in a raceway open ponds can be a promising method to increase the biomass productivity of a microalgal culture while reducing the production costs of biomass and the desired high-value product.

APA, Harvard, Vancouver, ISO, and other styles

5

El, Mouedden Yamna. "Lifetime and efficiency improvement of organic luminescent solar concentrators for photovoltaic applications." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2016. https://ro.ecu.edu.au/theses/1779.

Full text

Abstract:

In order to achieve the goal of zero net-energy consumption in residential and commercial buildings, substantial research has been devoted to developing methods for energy harvesting from window glass that is capable of passing visible light through the windows of buildings while converting the unwanted invisible solar radiation into electricity. Research has focussed on two particular aspects, namely (i) the integration of thin-film technology for solar radiation transmission control and (ii) light guiding structures for solar radiation routing towards the edges of the glass window. Recently, photovoltaic (PV) solar cells have been investigated and promoted as products for converting solar energy into electricity. Due to the increased demand for renewable energy sources, the manufacture of PV panels’ arrays has advanced considerably. However, they cannot compete with fossil fuel or nuclear energy, due to the high cost of inorganic solar cells and their low power conversion efficiency (PCE). To lower the cost per installed capacity ($/Watt) and to use the complete solar spectrum, new PV technologies have been developed, such as solar concentrators. Among the many kinds of concentrators, luminescent solar concentrators (LSCs) have significant industry application potential. Materials used in LSCs are inexpensive, the solar cell size is reduced and no tracking of the sun is required. In an LSC, the incident sunlight is absorbed by luminescent species, such as fluorescent dyes, quantum dots or rare-earth ion embedded in the active layer (organic or inorganic), which re-emits light in random directions usually at longer wavelengths. In an ideal LSC, all the re-emitted light can be routed towards the edges, where the attached small-area solar cells harvest the light and convert it into electricity. In this thesis, several contributions are made toward the development of organic LSCs. The first contribution is related to the design and development of multilayer thin film structures containing dielectric and metal layers, using physical vapour deposition, for the control of thermal and solar radiation propagated through glass windows. Measured transmittance spectra for the developed thin-film structures are in excellent agreement with simulation results. For the second contribution, a cost-effective, long-life-time organic LSC device with UV epoxy as a waveguide layer doped by two organic materials is developed. A PCE as high as 5.3% and a device lifetime exceeding 1.0×105 hrs are experimentally achieved. The third contribution of the thesis is the development of a general method for encapsulating organic LSCs, based on employing three optically transparent layers, (i) an encapsulating epoxy layer and (ii) two insulating SiO2 layers that prevent the dye dissolving into the epoxy layer. The encapsulated organic LSCs demonstrate an ultra-long lifetime of ~ 3.0×104 hrs and 60% transparency when operated in an ambient environment, of around 5 times longer than that of organic LSCs without encapsulation. Finally, the last contribution of the thesis is the development of a new LSC architecture that mitigates the reabsorption loss typically encountered in LSCs. Experimental results demonstrate significant reduction in photon reabsorption, leading to a 21% increase in PCE, in comparison with conventional LSCs.

APA, Harvard, Vancouver, ISO, and other styles

6

Bose, Rahul. "Raytrace simulations and experimental studies of luminescent solar concentrators." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/23272.

Full text

Abstract:

The luminescent solar concentrator is a planar, non-tracking device. Originally introduced more than three decades ago, it has yet to establish itself as a means of making photovoltaic solar energy more cost effective. Advances in organic luminescent centres, the emergence of inorganic nanocrystals and the development of new light trapping techniques have created promising opportunities for the LSC. This thesis investigates novel geometries and materials for the practical exploitation of LSCs. The research is based on experimental measurements as well as computational simulations using a Raytrace Model. It is shown both experimentally and computationally that a thin- lm structure produces the same effciency as a homogeneously doped LSC. Two building integrated applications are examined. The rst one is a power generating window employing a Lumogen Violet dye that absorbs short wavelength radiation and is mostly transparent in the visible. Annual yields of over 23 kWh/m2 and a conversion effciency of over 1% are predicted for a 50 cm by 50 cm device. The second BIPV application is the light-bar, which is designed to act as the secondary concentrator in a Venetian blind-like system. With linear Fresnel lenses producing a primary concentration factor of 20, an optimised system could generate nearly 60W/m^2 of power at an effciency of nearly 6% using direct sunlight only. Two novel luminescent materials, nanorods and phycobilisomes have been tested for their potential to reduce re-absorption losses. Despite current practical limitations, these materials are found to be promising due to enhanced Stokes shifts. LSCs with optical concentrations of 10 to 20 could be feasible by addressing the key shortcomings in the form of unabsorbed light and escape cone losses. Their versatility with regards to shape, colour and light absorption makes LSCs particularly relevant for building integrated photovoltaics.

APA, Harvard, Vancouver, ISO, and other styles

7

Sholin, Veronica. "Luminescent solar concentrators and all-inorganic nanoparticle solar cells for solar energy harvesting /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2008. http://uclibs.org/PID/11984.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Rosenberg, Ron S. B. Massachusetts Institute of Technology. "Dye-doped polymer nanoparticles for flexible, bulk luminescent solar concentrators." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81143.

Full text

Abstract:

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 52-56).
Bulk luminescent solar concentrators (LSC) cannot make use of Forster resonance energy transfer (FRET) due to necessarily low dye concentrations. In this thesis, we attempt to present a poly-vinylalcohol (PVA) waveguide containing dye-aggregate polystyrene nanospheres that enable FRET at concentrations below that required for the bulk LSC due to dye confinement. In the aqueous state, the maximum achieved energy transfer efficiency of the dye-doped nanoparticles was found to be 8 7% for lwt%/lwt% doping of Coumarin 1 (C1) and Coumarin 6 (C6). In the solid state, however, energy transfer is lost, reducing to 32.8% and 20.1% respectively for the C1(lwt%)/C6(lwt%) and C1(0.5wt%)/C6(lwt/ ) iterations, respectively. Presumably, the dyes leach out of the polystyrene nanospheres and into the PVA waveguide upon water evaporation during drop casting.
by Ron Rosenberg.
S.B.

APA, Harvard, Vancouver, ISO, and other styles

9

Correia, Sandra Filipa Henriques. "Organic-inorganic hybrid materials for green photonics: luminescent solar concentrators." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/17407.

Full text

Abstract:

Doutoramento em Física
Luminescent solar concentrators are inexpensive devices that aim to increase the efficiency of photovoltaic cells and promote the urban integration of photovoltaic devices, with unprecedented possibilities of energy harvesting through the façade of buildings, urban furniture or wearable fabrics. Generally, they consist of a transparent matrix coated or doped with active optical centres that absorb the incident solar radiation, which is re-emitted at a specific wavelength and transferred by total internal reflection to the edges where the photovoltaic cells are located. The main objective of this work is the production of luminescent solar concentrators whose optically active layer is based on organic-inorganic hybrid materials doped with europium ions or organic dyes, in particular, Rhodamine 6G and Rhodamine 800. Rhodamine 800, as opposed to europium ions and Rhodamine 6G which emit in the visible range, emits in the near infrared (NIR) range, which is an advantage for crystalline Si-based photovoltaic cells, whose efficiency is greater in the NIR. In this work, although the luminescent solar concentrators with planar geometry are addressed, the main focus is the use cylindrical geometry. The use of this type of geometry allows the effect of concentration to be higher relative to the planar geometry, since the ratio between the exposed area and the area of the edges is increased. The cylindrical geometry is exploited by producing luminescent solar concentrators based on polymer optical fibre (plastic) where the optically active layer is on the outside (as a coating) or inside (as a filling in the hollow core) of the optical fibre. Furthermore, the possibility of increasing the exposed area was also dealt with the production of bundles of luminescent solar concentrators in which the plastic optical fibres are placed side by side and, also, by fabricating luminescent solar concentrators with length in the metre scale.
Os concentradores solares luminescentes são dispositivos de baixo custo que têm como objetivo aumentar a eficiência de células fotovoltaicas e promover a integração de dispositivos fotovoltaicos em elementos do dia-a-dia, tornando possível a captura de energia solar, através da fachada de edifícios, mobiliário urbano ou em têxteis. Geralmente, consistem numa matriz transparente coberta ou dopada com centros óticos ativos, capazes de absorver a radiação solar incidente e reemiti-la com um comprimento de onda específico que será transportada, através de reflexão interna total, para as extremidades da matriz onde se encontra(m) a(s) célula(s) fotovoltaica(s). O principal objetivo deste trabalho consiste na produção de concentradores solares luminescentes cuja camada ótica ativa é baseada em materiais híbridos orgânicos-inorgânicos dopados com iões lantanídeos (európio, Eu3+) ou corantes orgânicos, nomeadamente, Rodamina 6G e Rodamina 800. A Rodamina 800, ao contrário dos iões de európio e da Rodamina 6G que emitem na gama do visível, emite na região espetral do infravermelho próximo (NIR), que se revela uma vantagem quando a célula fotovoltaica em uso é composta de silício cristalino, cuja gama de maior eficiência é no NIR. Neste trabalho, apesar de serem abordados concentradores solares luminescentes com geometria planar, o principal foco é a utilização da geometria cilíndrica. Este tipo de geometria permite que o efeito de concentração seja superior, relativamente à geometria planar, uma vez que a razão entre a área exposta e a área das extremidades é aumentada. A geometria cilíndrica é explorada, através da produção de concentradores solares luminescentes com base em fibra ótica polimérica (plástica) em que a camada ótica ativa se encontra no exterior (como um revestimento) ou no interior (como um preenchimento do núcleo oco). Além disso, a possibilidade de aumentar a área exposta foi, também, abordada com o fabrico de uma matriz de concentradores solares luminescentes colocados lado a lado e, também, com o fabrico de concentradores solares luminescentes na escala do metro.

APA, Harvard, Vancouver, ISO, and other styles

10

Mulder, Carlijn Lucinde. "Engineering the optical properties of luminescent solar concentrators at the molecular scale." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/71482.

Full text

Abstract:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 121-128).
Luminescent Solar Concentrators (LSCs) concentrate solar radiation onto photovoltaic (PV) cells using an inexpensive collector plate to absorb incoming photons and waveguide fluorescently re-emitted photons to PVs at the edge. This thesis addresses the two main energy loss mechanisms in LSCs, namely transport losses and trapping losses. We used phycobilisomes, a biological light-harvesting complex, as dyes in the LSC collector to circumvent transport losses caused by photon re-absorption. The selfassembled structure of phycobilisomes couples numerous donor chromophores to a handful of acceptor chromophores through an internal F6rster energy pathway that isolates the absorption and emission spectra. We established that energy transfer within intact phycobilisomes reduces LSC self-absorption losses by approximately (48±5)% by comparing intact and partly decoupled phycobilisome complexes. To reduce trapping losses in LSCs, we leveraged the anisotropic emission pattern of dichroic dye molecules. We aligned their dipole moments normal to the face of the waveguide by embedding them in a liquid crystal host. Vertical dye alignment increased the fraction of the power emitted below the critical angle of the waveguide, thereby raising the trapping efficiency to 81% from 66% for LSCs with unaligned dyes. The enhanced trapping efficiency was preserved for geometric gains up to 30, and an external diffuser can enhance absorption in LSCs with vertically-aligned dyes. This thesis also explores an energy harvesting strategy for portable electronics based on LSCs with dye molecules that are aligned in-plane. The purely absorptive polarizers used to enhance contrast ratios in displays can be replaced with two linearly polarized luminescent concentrators (LSCs) that channel the energy of absorbed photons to PVs at the edge of the display. We coupled up to 40% of incoming photons to the edge of a prototype LSC that also achieved a polarization selection ratio of 3. Finaly, we investigated the contribution of self-absorption and optical waveguiding to triplet exciton transport in crystalline tetracene (Tc) and rubrene (Rb). A timeresolved imaging technique that maps the triplet distribution showed that optical waveguiding dominates over diffusion and can transport energy several micrometers at the high excitation rates commonly used to probe the exciton diffusion constants in organic materials.
by Carlijn Lucinde Mulder.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

11

Wilson, Lindsay Robert. "Luminescent solar concentrators : a study of optical properties, re-absorption and device optimisation." Thesis, Heriot-Watt University, 2010. http://hdl.handle.net/10399/2336.

Full text

Abstract:

This thesis presents the results of work on the optical properties and design optimisation of the luminescent solar concentrator (LSC). The optical properties of a range of uorophores were measured and it was found that the Lumogen F Rot 305 organic dye exhibited properties which make it ideal for use in LSCs, namely a wide absorption range (300-650 nm), 100% quantum yield at concentrations up to 1700 ppm, and the highest photostability of all the Lumogen F dyes, although the overlap of the absorption and emission spectra results in reabsorption (RA) losses. Despite these optimum properties, a detailed analysis showed that LSCs based on Rot 305 cannot compete with conventional glass/glass laminate modules on grounds of either cost or embodied energy. Since Rot 305 represents an optimum dye, this suggests it is unlikely that LSCs based on organic dyes will ever be competitive with conventional technologies. The only solution is the use of a uorophore with greatly reduced RA losses, for example a rare-earth (RE) complex. The RA losses of a europium-containing complex were found to be less than those of the Rot 305 dye, despite the lower quantum yield of the complex (86 %). The solar-to-electric conversion e ciencies of several LSC modules based on Rot 305 were measured. Modules with dimensions of 10 cm x 10 cm and 60 cm x 60 cm had e ciencies of 2.7% and 1.84% respectively, both measured without a back re ector. In addition, the technique of current-matching the edge cells was successfully demonstrated, resulting in a 15% increase in power output from an edge using matched cells relative to an edge using unmatched cells.

APA, Harvard, Vancouver, ISO, and other styles

12

CAPITANI, CHIARA. "Synthesis of semiconductor colloidal nanocrystals with large Stokes-shift for luminescent solar concentrators." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2022. http://hdl.handle.net/10281/366195.

Full text

Abstract:

I concentratori solari luminescenti (LSCs) sono delle guide d’onda composti da una matrice polimerica drogata o ricoperta con fluorofori. La luce solare diretta e/o diffusa che penetra nella matrice è assorbita dai fluorofori e poi riemessa dagli stessi con energia minore. La luce emessa, grazie alla riflessione totale interna, propaga fino a raggiungere i bordi della guida d’onda dove è convertita in elettricità da celle fotovoltaiche poste sul perimetro della matrice. L’efficienza del dispositivo è ridotta da numerosi processi di perdita, sia dovuti alla riflessione della matrice e al cono di fuga, sia quelli che dipendono dalle caratteristiche dei fluorofori, come il coefficiente di assorbimento, il quantum yield (QY) di fotoluminescenza (PL) e il riassorbimento. Per minimizzare tali perdite, una buona alternativa ai tradizionali fluorofori sono i quantum dots (QDs) colloidali che presentano solitamente un elevato QY, un alto coefficiente di assorbimento e una lunghezza d’onda di emissione controllabile cambiando le dimensioni dei nanocristalli tramite modifiche dei parametri di sintesi. Inoltre, ingegnerizzando opportunamente i QDs, è possibile realizzare particelle con elevato Stokes-shift tra gli spettri di assorbimento ed emissione, in modo da ridurre quanto più possibile il riassorbimento. Il progetto si è quindi focalizzato sullo sviluppo della sintesi di QDs, al fine di ottimizzare il QY di fotoluminescenza, la compatibilizzazione con la matrice polimerica e la fotostabilità, limitando comunque il riassorbimento. Inoltre. la procedura di sintesi deve essere facilmente trasportabile su volumi industriali, per soddisfare il fabbisogno di produzioni di elevati metri quadrati di LSCs. Durante i tre anni di progetto di dottorato in Alto Apprendistato ho potuto sviluppare una procedura di sintesi che consiste in quattro step: • crescita di nanocristalli di CuInS2 core; • formazione del quaternario tramite aggiunta di zinco (ZnCuInS2); passaggio cruciale per aumentare il QY e controllare la lunghezza d’onda di emissione; • crescita di una shell di solfuro di zinco (ZnCuINS2/ZnS) per passivare la superficie dei nanocristalli, aumentare il QY e la fotostabilità; • trattamento post sintesi di scambio di leganti parziale per migliorare la solubilità nella matrice polimerica. I nanocristalli così prodotti mostrano un QY del 60% ed un’ottima solubilità nella matrice polimerica. Infatti, è stato prodotto un LSC di grande dimensione (30 cm x 30 cm x 0.7 cm) la cui optical power efficiency, OPE = 6.8%. Inizialmente ho sviluppato la procedura di sintesi in un pallone di vetro da 25 mL, producendo 250 mg a sintesi. Grazie all’attrezzatura fornita da Glass to Power S.p.A ho potuto studiare lo scale-up della sintesi. Dapprima ho effettuato studi preliminare, per approfondire alcune possibili problematiche dovute all’aumento dei volumi, su palloni di maggiori dimensioni, 500 mL e 2 L. Analizzate e risolte le tematiche di riscaldamento e stop della sintesi ho effettuato sintesi in un reattore preindustriale producendo 300 g di nanocristalli di ZnCuINS2/ZnS. Oltre ad incrementare la produzione di sintesi da 250 mg a 300 g mi sono occupata dell’ottimizzazione della procedura di sintesi. Ho testato diverse strategie per incrementare il QY senza danneggiare la solubilità nel polimero. Grazie ad una variazione di reagente nel secondo step e ad un incremento dei layer della shell ho ottenuto nanocristalli con 80% di QY. Il prossimo step sarà effettuare lo scale-up di questa nuova procedura e produrre LSC di grandi dimensioni. Grazie alle collaborazioni con altri studenti di dottorato ho sintetizzato nanocristalli di calcogenuro drogati oro e opportunamente decorati con molecole coniugate per sistemi di up-conversion. Grazie all’introduzione dell’oro in questi sistemi si è ottenuta un’efficienza di up-conversion del 12%.
Luminescent solar concentrators (LSCs) are waveguides composed of a polymeric matrix doped or coated with fluorophores. The direct and/or diffuse sunlight that penetrates the matrix is absorbed by the fluorophores and then re-emitted by them with less energy. The light emitted, thanks to the total internal reflection, propagates until it reaches the edges of the wave guide where it is converted into electricity by photovoltaic cells placed on the perimeter of the matrix. The efficiency of the device is reduced by numerous loss processes, due to the reflection of the matrix and the escape cone, and/or due to the characteristics of the fluorophores, such as the absorption coefficient, the quantum yield (QY) of photoluminescence (PL) and the reabsorption. To minimize losses due to fluorophores, a good alternative are colloidal quantum dots (QDs) that usually have a high QY, a high absorption coefficient and a controllable emission wavelength by changing the size of the nanocrystals. Furthermore, by properly engineering the QDs, it is possible to realize particles with high Stokes-shift between the absorption and emission spectra, in order to reduce the reabsorption as much as possible. The project is focused on the development of the synthesis of QDs, in order to optimize the QY of photoluminescence, compatibility with the polymer matrix and photostability, while limiting the reabsorption. Besides. the synthesis procedure must be easily transferable on industrial volumes, to meet the production needs of high square meters of LSCs. During the three years of the doctoral project in High Apprenticeship I was able to develop a synthesis procedure consisting of four steps: • growth of CuInS2 core nanocrystals; • quaternary formation with zinc addition (ZnCuInS2); crucial step to increase the QY and control the emission wavelength; • growth of a zinc sulphide shell (ZnCuInS2/ZnS) to passivate the surface of nanocrystals, increase QY and photostability; • post-synthesis treatment of the partial exchange of ligands to improve solubility in the polymer matrix. The nanocrystals thus produced show 60% QY and excellent solubility in the polymer matrix. In fact, a large size LSC (30 cm x 30 cm x 0.7 cm) was produced, whose optical power efficiency, OPE = 6.8%. Initially, I developed the synthesis procedure in a 25 ml glass flask, producing 250 mg for batch. Thanks to the equipment provided by Glass to Power s.p.A I was able to study the increase in the scale of the synthesis. Firstly, in order to investigate some possible problems due to the increase in volumes, I have carried out preliminary studies on larger balloons, 500 mL and 2 L. After analysis of heating and quenching of synthesis, I have performed the synthesis in a preindustrial reactor producing 300 g of nanocrystals of ZnCuInS2/ZnS. In addition I also optimized the synthesis procedure. I tested several strategies to increase QY without damaging solubility in the polymer. Thanks to a variation of the reagent in the second step and an increase of the shell layers, I obtained nanocrystals with 80% of QY. The next step will be to scale up this new procedure and produce large LSCs. I collaborated with other PhD students, in particular, I synthesized with a heat-up method CdSe nanocrystals doped with Au7 clusters and decorated with conjugated dyes as efficient triplet sensitizers or up-conversion applications (gold doping improves up-conversion efficiency). The beneficial effects of the doping strategy result in a maximum UC efficiency of 12%, which is an unprecedented result for up-conversion based on decorated NCs as triplet sensitizers.

APA, Harvard, Vancouver, ISO, and other styles

13

Congiu, Martina. "Synthesis and characterisation of luminescent lanthanide dyes for solar energy conversion." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7724.

Full text

Abstract:

Lanthanide (III) complexes are used extensively in solar conversion devices, such as Luminescent Solar Concentrators (LSCs) and Luminescent Down-Shifting (LDS) for their peculiar characteristics of narrow band emission, avoidance of re-absorption losses due to large Stokes shift and possibility of high photoluminescence quantum yield (PLQY). The study has looked into the synthesis of Ln (III) complexes of the general formula: [Ln(hfac)3DPEPO], where DPEPO = bis(2-(diphenylphosphino)phenyl)ether oxide, and hfac = hexafluoroacetylacetonate. The work presented in this thesis focuses on the synthesis, and subsequent photophysical characterisation of these Ln(III) complexes, plus characterisation and spectroscopic study of [Tb(pobz)3(hacim)2], (where Hpobz = phenoxybenzoic acid, and Hacim = acetylacetone imine), yielding results that open new design of functional Ln(III) systems. Spectroscopic study of Chromium dioxalate and analogous compounds has revealed that with the appropriate design, Cr(III)Ln(III) energy transfer can be achieved, while study of polyaromatic hydrocarbons (PAH) such as coronene, enable to explore a ligand with better absorption in the whole UV region. These results open attractive perspectives for light-conversion systems, such as LSC devices.

APA, Harvard, Vancouver, ISO, and other styles

14

Gutmann, Johannes [Verfasser], and Hans [Akademischer Betreuer] Zappe. "Photonic luminescent solar concentrators : : how photonic crystals affect the emission and guiding of light = Photonische Fluoreszenzkonzentratoren." Freiburg : Universität, 2014. http://d-nb.info/1123484880/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Marianetti, Giulia. "Synthesis, optical characterization and computational study of novel organic fluorophores." Doctoral thesis, Scuola Normale Superiore, 2017. http://hdl.handle.net/11384/85811.

Full text

Abstract:

Over the last three decades lot of interest has been devoted to light harvesting technologies. Recent findings on global warming and energy nonrenewable resources push us to alternative means of storing energy. Sunlight stands indeed as an ideal asset to take advantage of. In this insight Luminescent Solar Concentrators (LSCs) represent a way to decrease the cost of solar photovoltaics. LSC devices usually consist in a thin slab of transparent material (glass or polymer) doped with a fluorescent dye. Upon solar irradiation, a fraction of the emitted light, through means of internal reflection, is collected at the edges of the device where photovoltaic cells are located. Compared to traditional concentrators, which make use of mirrors and lenses, these devices show numerous advantages, such as theoretical higher concentration factors, the ability to work with both diffuse and incident light and no need for tracking devices or cooling apparatuses. Organic fluorescent dyes bearing π-conjugated electron-donor and -acceptor moieties exhibit intramolecular charge-transfer (ICT) properties, and can therefore show the optical properties required by LSCs such as high quantum yield and high Stokes shift. On account of this, the present dissertation will discuss the synthesis, UV-Vis characterization and computational study of a set of novel unsymmetrical and symmetrical push-pull azole-based dyes. These compounds are characterized by a 1,3-azole 2,5 substituted with two aromatic moieties bearing electron withdrawing (EWG) or electron donating (EDG) groups. Remarkably, the introduction of an heteroaromatic ring usually improves the thermal and chemical stability and the overall polarizability of the fluorophore. The studied compounds were prepared through a robust synthetic pathway involving a palladium and copper-promoted direct C-H arylation reaction as key step. We took into account the effect of the peripheral electron poor funtionality as well as the nature of the central heteroaromatic core. In order to rationalize the experimental results we carried out TD-DFT studies, that allowed us to proper understand the charge tranfer occuring during the electronic transition. After selecting the best fluorophores for our aim, we investigated its efficiency in an LSC prototypes.

APA, Harvard, Vancouver, ISO, and other styles

16

Freitas, Vânia Patrícia Castro Teixeira. "Organic-inorganic hybrids for green photonics." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17325.

Full text

Abstract:

Doutoramento em Física
The presente work aims to synthesize new bridge silsesquioxanes organic-inorganic hybrid materials, and characterize the local structure and photoluminescence properties overlooking potential applications in the area of green photonics, namely, in solid-state lighting and luminescent solar concentrators. In this context, three distinct families of materials based on six precursors which differ in their structural organization were synthesized, i.e. precursors with structure: 1) linear where the organic component is based on malonamide group, P2-m and P4-m; 2) linear which has been added an aromatic ring whose organic part is based on amide and/or thioamida, P(UU), P(UT) and P(TT) and 3) branched which the organic component is based on amide group, t-UPTES (5000). Two organic-inorganic hybrids (M2-m e M4-m) which results from hydrolysis and condensation of the precursors P2-m e P4-m were synthetized. The role of the presence of one or two malonamide groups was studied in terms of local structure and photoluminescence properties. Three organic-inorganic hybrids H(UU), H(UT) and H(TT) based on P(UU), P(UT) and P(TT) were synthesized and structurally characterized aiming to study the role of the hydrogen bond in the self-assembling of these materials. The presence of different types of hydrogen bonds (bifurcated, linear and cyclic) induces different conformations which affect the physical properties (mechanical and optical) of the materials. Hybrids based on t-UPTES(5000) precursor were synthesized based on different synthesis strategies. Changing the concentration of HCl and water content as well as the synthesis in a controlled environment allowed the improvement of the optical properties of this system, in particular, the absolute emission quantum yield and the absorption coefficient. In addition, it were studied the recombination mechanisms responsible for the emission through the comparison between the corresponding photoluminescence properties of the organic and inorganic models. Finally, due to the structural simplicity of the precursors P2-m and P4-m, these were doped with Eu3+. The local structure of the corresponding hybrids shows local coordination between the ion and the host. Efficient materials concerning the absolute emission quantum yield values motivated the development of luminescent solar concentrators with a maximum absolute emission quantum yield of 0.600.06 and optical conversion efficiency in the absorption spectral region (300-380 nm) of 12.3%.
O presente trabalho propõe sintetizar novos materiais híbridos orgânicos-inorgânicos do tipo silsesquioxanos em ponte e caracterizar a sua estrutura e propriedades de fotoluminescência com vista a potenciais aplicações na área da fotónica sustentável, nomeadamente, iluminação de estado sólido e concentradores solares luminescentes. Neste âmbito, foram sintetizadas três famílias distintas de materiais baseados em seis precursores que diferem na sua organização estrutural, ou seja, precursores com estrutura: 1) linear onde a componente orgânica é baseada no grupo malonamida, P2-m e P4-m; 2) linear onde foi adicionado um anel aromático cuja componente orgânica é baseada em amida e/ou thioamida, P(UU), P(UT) e P(TT), e 3) tri-ramificada onde a componente orgânica é baseada no grupo amida, t-UPTES(5000). Dois híbridos orgânicos-inorgânicos (M2-m e M4-m) que resultam da hidrólise e condensação dos precursores P2-m e P4-m foram sintetizados. O papel da presença de um ou dois grupos malonamida foi estudado em termos de estrutura local e propriedades de fotoluminescência. Três híbridos orgânicos-inorganicos, H(UU), H(UT) e H(TT), baseados, respetivamente, em P(UU), P(UT) e P(TT), foram sintetizados e caracterizados estruturalmente com o objetivo de estudar o papel das ligações de hidrogénio na auto-organização destes materiais. A presença de diferentes tipos de ligações de hidrogénio (bifurcada, linear e cíclica) induz diferentes tipos de configurações que têm influência nas propriedades físicas (mecânicas e óticas) dos materiais. Híbridos baseados no precursor t-UPTES(5000) foram sintetizados tendo em conta diferentes estratégias de síntese. A variação da concentração de HCl e quantidade de água bem como a síntese em ambiente controlado permitiram melhorar as propriedades óticas deste sistema nomeadamente, o rendimento quântico absoluto e o coeficiente de absorção. Foram também discutidos, os mecanismos de recombinação responsáveis pela emissão através da comparação das propriedades de fotoluminescência observadas nos correspondentes modelos orgânicos e inorgânicos. Finalmente, devido à simplicidade estrutural os precursores P2-m e P4-m, estes foram dopados com Eu3+. A estrutura local dos correspondentes híbridos mostra coordenação local entre o ião e a matriz. Materiais eficientes do ponto de vista de rendimento quântico absoluto motivaram o desenvolvimento de concentradores solares luminescentes que apresentam rendimento quântico absoluto máximo de 0.600.06 e eficiência ótica de conversão na região espetral de absorção (300-380 nm) de 12.3 %.

APA, Harvard, Vancouver, ISO, and other styles

17

Kaysir, Md Rejvi. "Novel luminescent solar concentrator utilizing stimulated emission." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16477.

Full text

Abstract:

Luminescent Solar Concentrators (LSCs) are an emerging technology that aims primarily to reduce the cost of photovoltaic (PV) power generation, with great potential for building-integrated photovoltaics (BIPV) system. Commercial realization of these devices is mainly hampered by reabsorption loss. This work describes a novel method of reducing the reabsorption as well as improving the directional emission utilizing stimulated emission, rather than only spontaneous emission as in standard LSCs, by using a seed laser. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire area of the LSC panel, modifying the emission spectrum of the photoexcited luminophores such that it is spectrally narrower, at a wavelength that minimizes reabsorption and allows a net gain in the system, and is directed towards a small PV cell, anticipated to be ~ 1 mm2. A fraction of the PV cell’s output power is fed back to the seed laser; i.e. the system acts as a closed loop system. This thesis reports the design and working principle of a stimulated-LSC (s-LSC) and the development of a mathematical model to identify important physical parameters for the practical realization. Also, a novel method to characterize the luminophores for the s-LSC system is developed using a parameter called ‘stimulated gain coefficient.' Finally, this concept has been explored with the known photostable Perylene Red (PR) dyes for the proof of principle. The experimental results are well-matched with the model except for the gain saturation with a comparatively small seed laser signal power. To investigate this gain saturation, two approaches were taken: investigating (i) spectral hole burning and (ii) triplet state absorption. None of the existing luminophores investigated show the required characteristics for the s-LSC system. However, there is a plenty of room for the innovation of luminophores to realize a practical s-LSC system.

APA, Harvard, Vancouver, ISO, and other styles

18

BERNARDONI, Paolo. "Performance Optimization of Luminescent Solar Concentrator Photovoltaic Systems." Doctoral thesis, Università degli studi di Ferrara, 2016. http://hdl.handle.net/11392/2403385.

Full text

Abstract:

Lo scopo di questo lavoro è l'ottimizzazione di sistemi fotovoltaici basati su concentratori solari a luminescenza, questi dispositivi non sono di nuova concezione ma, al momento, non è ancora disponibile un'analisi approfondita di sistemi dalle dimensioni adatte alla costruzione di dispositivi per integrazione architettonica. Per questa ragione, in questo lavoro, vengono analizzate le prestazioni di LSC costruiti impiegando diversi pigmenti, dimensioni e configurazioni ottiche così come l'effetto dell'auto-assorbimento sullo spettro di emissione del dispositivo, inoltre le differenti configurazioni ottiche sono state anche sottoposte a diverse condizioni di ombreggiamento così da identificare la più efficiente non solo in condizioni di lavoro ideali ma anche in uno scenario più simile alle reali condizioni di impiego di un dispositivo mirato all'integrazione architettonica. I prototipi sono stati costruiti a seguito di un ampio lavoro di simulazione del loro comportamento ottico mirato alla selezione delle configurazioni più promettenti, in particolare non è stata tenuta in considerazione solo l'efficienza ma anche la scalabilità del progetto e la facilità di assemblaggio: caratteristiche importanti per un prototipo che dovrebbe essere oggetto di trasferimento tecnologico dalla ricerca all'industria. Il primo risultato ottenuto è la dimostrazione della fattibilità di LSC di grandi dimensioni, ben oltre la comune dimensione da laboratorio di 5x5cm, inoltre, si è anche dimostrato come le prestazioni degli LSC possano essere incrementate con una contemporanea riduzione dei costi applicando pellicole riflettenti sui bordi così da uniformare il profilo di irradianza sulle celle. Tuttavia il risultato più significativo ottenuto è di aver dimostrato come sistemi con un ridotto numero di celle accoppiate a pellicole riflettenti poste sui lati rimanenti dell'LSC possano fornire un'efficienza maggiore rispetto ai sistemi tradizionali con le celle posizionate su quattro lati. Questi sistemi hanno anche mostrato una minore sensibilità agli effetti dell'ombreggiamento che rappresenta un risultato fondamentale per una tecnologia mirata all'integrazione architettonica, sottolineandone il progresso da argomento di ricerca a tecnologia con buone premesse di trasferimento verso l'industria.
The purpose of this work is the optimization of photovoltaic systems based on luminescent solar concentrators, these devices are not a new concept but, so far, a thorough analysis of the performance of LSC systems with sizes practical for building integration applications is missing. For this reason in this work the performances of LSCs based on different dyes, different sizes and various optical configurations were analysed as well as the effect of self-absorption on the output spectrum, moreover the performances of the systems with different optical configurations were analysed under some possible shading conditions in order to identify the most efficient and convenient design non only under an ideal working exposure but also in a real world scenario. The prototypes were built after an extensive work of simulation of their optical behaviour aimed at selecting the most promising designs, in particular not only the efficiency has been taken into account but also the scalability of the modules to larger or smaller sizes and the ease of assembly: important features for a design that should undergo a technology transfer from research to industrialization. The first result obtained is that the feasibility of large size LSCs (up to one square metre) well above the common laboratory size of 5×5cm have been demonstrated, moreover, it has also been shown that the performances of LSC systems can be improved, while lowering cost at the same time, by using reflective layers to get a more uniform irradiance profile on the cells. Anyway the most remarkable result obtained so far is having demonstrated that systems employing a small number of cells and a reflective film on the remaining sides of the LSC can yield a higher efficiency than a traditional design with cells placed on four sides, moreover these systems have also demonstrated a lower sensitivity to shading losses which represents a fundamental result for a technology targeted at the building integration, highlighting the progress of luminescent solar concentrators from a mere laboratory research topic to a promising industrialisable technology.

APA, Harvard, Vancouver, ISO, and other styles

19

Alghamedi, Ramzy. "Luminescent solar concentrator structures for solar energy harvesting and radiation control." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2017. https://ro.ecu.edu.au/theses/1965.

Full text

Abstract:

Luminescent solar concentrators are devices capable of converting some spectral components of solar radiation by luminescence and concentrating them before collection by photovoltaic. The aim of this thesis is to design, develop and demonstrate the principle of all-inorganic semitransparent luminescent solar concentrator (LSC) structures capable of passing most of the visible light through to provide illumination, while reflecting more than 90% of the UV and IR radiations and scattering them to the edges of the glass where they are collected by PV cells to produce electricity. All-inorganic visibly-transparent energy-harvesting clear laminated glass windows are the most practical solution to boosting building-integrated photovoltaics (BIPV) energy outputs significantly while reducing cooling- and heatingrelated energy consumption in buildings. A typical semitransparent luminescent solar concentrator is based on the integration of micro-engineered optical structures, nano-materials and IR-selective thin-film coatings, to realise stable, long-lifetime and shatterproof clear glass panels. The ability of the proposed semitransparent luminescent solar concentrators to generate electricity addresses the future net-zero-energy building demand [1, 2], making them ideal candidates for future high-rise glass buildings. The developed semitransparent luminescent solar concentrators employ low-e thin films, which particularly, provide many benefits, including, (i) building overall aesthetic appearance, (ii) low glare and (iii) filtration of unwanted components of the incident sunlight thus increasing the energy saving rating of buildings. The low-e glass panes are typically used in a double glazing structure in order to protect the low-e film from environmental impacts and improve the insulation properties of the semitransparent luminescent solar concentrators in addition to reducing the energy consumed for cooling or heating the inside of buildings. Multi-layer thin film coatings for solar and thermal radiation control are designed, using the Optilayer software package, developed using Physical Vapour Deposition (PVD), and tested using spectrophotometry. Experimental results show that the measured transmittance spectra for the developed structures are in agreement with simulation results and demonstrate that with the use of optimum metal-dielectric layer combination it is possible to transmit/reflect arbitrary spectral components of the incident sunlight. In addition, two types of semitransparent luminescent solar concentrator structures are designed, developed and characterised, namely: 1. LSCs incorporating inorganic luminophore materials into the lamination interlayer. These luminophores, when used in conjunction with spectrally-selective low-e thin-film coatings and CuInSe2 solar cells, enable most of the visible solar radiation to be transmitted through the glass window with minimum attenuation and the ultraviolet (UV) radiation to be down-converted and routed together with a significant part of infrared radiation to the edges for collection by solar cells. 2. Advanced LSCs incorporating inorganic luminophore materials as well as spectrallyselective diffraction gratings as light deflector structures of high visible transparency into the lamination interlayer. For these LSCs, most of the visible solar radiation can be transmitted through the glass windows with minimum attenuation while the ultraviolet (UV) and a part of incident solar infrared (IR) radiation energy are converted and/or deflected geometrically for routing towards the vicinity of glass panel edge regions for collection by solar cells. To boost the solar concentration capability of the laminated glass panes, functionalized epoxy interlayers are especially developed, which comprise UV-curable epoxy and inorganic luminophores with engineered absorption and emission bands. The developed functionalized interlayers demonstrate an excellent ability to scatter and concentrate sunlight within the glass structure with minimum reabsorption. Several materials and combinations of several luminophore types were investigated in order to determine the optimum interlayer structure that exhibits maximum UV and IR radiation scattering, conversion, and deflection towards the edge solar cells. Measured conversion efficiencies of 3.8% and 5.4% are achieved for 10 cm × 10cm LSCs samples without and with diffraction gratings, which correspond to output electrical power densities of 38Wp/m2 and 54 Wp/m2,respectively. A photobioreactor based on the developed semitransparent luminescent solar concentrator technology is developed, in collaboration with Murdoch University, for microalgae growth. An Insulated Glass Units (IGU) employing a special low-e thin film is developed, which passes more than 50% of the visible light while blocking more than 90% of the UV and IR radiations, hence, reducing the temperature inside the photobioreactor and improving the microalgae growth. The growth and productivity of the microalgae in the Insulated Glass

APA, Harvard, Vancouver, ISO, and other styles

20

MacQueen, Rowan. "Spectral management for quantum solar energy harvesting: changing the colour of the sun." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11784.

Full text

Abstract:

The study and deployment of solar energy conversion systems are justified on many grounds: environmental, economic, geopolitical, and societal. Collectively, these justifications provide a dynamic and compelling backdrop for the continuing narrative of solar energy. The energy conversion efficiency of a solar cell is set by the design of the cell and by the properties of the incident sunlight. Thus in addition to works aimed at improving solar cells directly, are those directed towards shaping the solar spectrum incident on the cell, prior to sunlight absorption. So-called spectral management is distinct from, but closely related to, solar cells. Two such techniques are documented here. The first, luminescent concentration, downshifts energy and concentrates photon flux within a luminophore-doped waveguide. Problems associated with luminescence concentrators are reported, motivating a novel arrangement of the light absorbing centers aimed at ameliorating lossy emission by induced photon anisotropy. We present the first experimentally-realised implementation of the design. The second portion of work concerns triplet-triplet annihilation upconversion (TTA-UC), a means by which sub-band gap photon losses in solar cells can be reduced. We present schemes for tethering TTA-UC absorbers to nanostructured solids in a bid to increase chromophore concentration and UC efficiency. Kinetic studies of these materials are presented. Results show the formation of heterogeneous structures dependent on the chromophore, binding mechanism and scaffold. Solar cell enhancement experiments were used to show the enhancement of a H-passivated a-Si solar cell by a solid-tethered upconverter, producing modest gains in short-circuit current. The action spectrum, a novel photoluminescence technique for measuring TTA-UC efficiency, was measured for two materials, and the results corroborated using rate measurements. The action spectrum is a promising new upconversion characterisation method.

APA, Harvard, Vancouver, ISO, and other styles

21

Low, Jeremy J. Xu Jian. "A general study of a colloidal quantum dot luminescent solar concentrator." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4775/index.html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Song, Fengchi. "Luminescent solar concentrator and photovoltaic module integrated system analysis and design." Thesis, Song, Fengchi (2017) Luminescent solar concentrator and photovoltaic module integrated system analysis and design. Honours thesis, Murdoch University, 2017. https://researchrepository.murdoch.edu.au/id/eprint/38693/.

Full text

Abstract:

This thesis report presents the analysis and design work associated with luminescent solar concentrators (LSC) and photovoltaic integrated systems in microalgae cultivation application, which is the dissertation topic of my graduation dissertation in Engineering major, Murdoch University. Around the main topic of LSCs, a few relevant studies have been carried out in sequence. To start with, the contents focus on brief introduction and theoretical analysis and they act as the foundation of the whole analysis. Therefore, the majority works of this part of analysis are finished by looking through literature works; a significant number of relevant articles are cited here. Afterwards, the data from experiment is expressed and presented. From the experiment’s data, the two specimen LSC, flat sheet LSC and hollow cylinder LSC can emit fluorescent light at bottoms up to 6.9 times and 1.85 times stronger than coinstantaneous sunlight illumination respectively. Moreover, when the sample photovoltaic cell is receiving the concentrated fluorescent light from the two LSCs, the cell can produce up to 4mW power from flat sheet LSC emission light irradiance and 13.5mW from tubular LSC emission irradiance. Another major achievement of this project is that an integrated system has been designed, which has the ability to supply the power requirement entirely by itself.

APA, Harvard, Vancouver, ISO, and other styles

23

Currie, Michael James. "Fabrication of a luminescent solar concentrator that minimizes self-absorption losses using inter-chromophore energy transfer." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40516.

Full text

Abstract:

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
Includes bibliographical references (p. 57-59).
The projected need for carbon-free power during this century is immense. Solar power offers the largest resource base to supply this need, but in light of recent silicon shortages, it is an open question whether silicon photovoltaics can keep pace with demand. The development of economical concentrators could relieve this resource pressure. The luminescent solar concentrator (LSC) is an architecture that collects and concentrates light using the luminescent properties of chromophores embedded in a waveguide. This method of concentration alleviates the need for expensive tracking equipment necessary for optical concentration. Combined with the low cost and flexible fabrication of organic materials, this technology is inherently scalable. A major limitation to LSC efficiency is self-absorption between different chromophores within the waveguide. Finding inspiration from the architecture of phycobilisome antenna complexes, a system of chromophores is developed that minimizes self-absorption through Firster energy transfer. Precise control of intermolecular spacing is achieved through thermal evaporation of small molecule organics. A LSC with a geometric gain of 25 is fabricated that employs this optimized system. External quantum efficiencies of 32% are achieved across nearly half the visible spectrum, with a total power conversion efficiency of 1.6%. Additionally, modeling and theory are presented to highlight places for device improvement. It is shown that a simple path integral successfully captures the dynamics of the LSC.
by Michael James Currie.
S.M.

APA, Harvard, Vancouver, ISO, and other styles

24

Thompson, Nicholas John. "Chromium (III), Titanium (III), and Vanadium (IV) sensitization of rare earth complexes for luminescent solar concentrator applications." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69674.

Full text

Abstract:

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 56-59).
High optical concentrations without excess heating in a stationary system can be achieved with a luminescent solar concentrator (LSC). Neodymium (Nd) and ytterbium (Yb) are excellent infrared LSC materials: inexpensive, abundant, efficient, and spectrally well-matched to high-performance silicon solar cells. These rare earth ions are reasonably transparent to their own radiation and capable of generating high optical concentrations. Neodymium's and ytterbium's disadvantage is their relatively poor absorption overlap with the visible spectrum. Transition metals such as chromium (Cr), titanium (Ti), and vanadium (V) have broadband absorption covering the visible and near-infrared and can efficiently sensitize neodymium and ytterbium through a non-radiative energy transfer process. Chromium, titanium, and vanadium containing glasses were fabricated using a custom designed glass making furnace. The optical properties including molar absorption coefficient, photoluminescence spectrum, and energy transfer characteristics were investigated to determine the suitability for LSC applications. Glasses containing Cr or V co-doped with Nd or Yb demonstrated energy transfer from the transition metal to the rare earth, a fundamental step toward integration into a LSC. Titanium co-doped glasses did not exhibit photoluminescence or energy transfer. Chromium co-doped glasses exhibit both forward and backward energy transfer. Vanadium holds the best promise as a sensitizer for LSC applications.
by Nicholas John Thompson.
S.M.

APA, Harvard, Vancouver, ISO, and other styles

25

MUTERI, Vincenzo. "Energy evaluation and life cycle assessment of an innovative building integrated technology: the smart window-luminescent solar concentrator." Doctoral thesis, Università degli Studi di Palermo, 2022. https://hdl.handle.net/10447/535303.

Full text

Abstract:

Luminescent Solar Concentrators (LSC) represent one of the innovative and potentially most versatile technologies related to Building Integrated Photovoltaics (BIPV). The peculiarity of these devices lies in the fact that they can be integrated into the surface of the building to replace openings such as skylights or windows, thanks to their characteristic of being semi-transparent and of functioning both with direct and diffused radiation. Eni developed the own technology Eni Ray Plus® based on LSC and integrated it in a multifunctional smart window-LSC (SW-LSC) prototype. The device uses the energy produced by LSC modules to power an autonomous and passive shading system, exploiting irradiation sensors, motors and batteries. It independently regulates the movement of the shading system and allows energy surplus, through the electricity generated by modules. The final aim of this thesis is to explore the energy performances of the SW-LSC prototype into the building and to determinate the life cycle environmental impacts of the device through the application of the Life Cycle Assessment methodology. In addition, the focus is to highlight the impacts of the LSC modules only, assuming that they can be applied into glazed buildings, and to compare them with those of other PV technologies on the market. The first part of the work is focused on SW-LSC optical, thermal and electrical performances, comparing them with those of a traditional window. The analysis followed an experimental approach that involved lighting and electrical monitoring studies in a real test room, in order to create validated models for conducting simulations in larger buildings. The results were expressed through the study of illuminance maps, electricity generation obtainable from the integrated photovoltaic technology and in terms of energy savings. In conclusion, the models created allowed to evaluate the performances of the new technology, providing useful information for energy saving strategies in buildings. The second part of the work regarded the evaluation of the life cycle impacts. The functional unit (FU) chosen was the whole SW-LSC (5,27 m2) considering its thermal and optical characteristics (Uw = 1,6 -1,8 W/m2K, tvis = 77% and g = 85% of LSC modules) and the possibility to produce about 1.5 kWh/year. The system boundary was from cradle to gate considering the assembly and maintenance phase, while the end of life (EOL) was considered separately through a recycling/landfill scenario. Results showed that global warming potential (100 years) for SW-LSC was 5.91E+03 kg CO2eq and the production phase had the greatest impact (about 96%). The EOL recycling/landfill scenario results showed the possibility to reduce impacts by an average of 45%. The dominance analysis of SW-LSC components showed that the aluminum frame was the main hotspot (about 60% contribution) in all categories (except in abiotic depletion potential, 16% contribution), followed by the light-shelf (about 19% contribution). The batteries and motors for the shading system were the biggest contributors in the abiotic depletion potential category (36% and 30%, respectively). Since the materials of the SW-LSC prototype are not yet optimized in an eco-design context, it is important to underline that other alternative materials will be taken into consideration during the marketing phase (such as the use of wood or a wood-aluminum combination for the frame). The alternative scenario, which involved the use of 75% recycled aluminum for the window frame, showed that it is possible to reduce environmental impacts from 3% to 46% (with a mean value of 33.6%). Finally, the results for the SW-LSC were compared with those of the EPDs of some traditional windows (the functional unit for the comparison was the m2). A further comparative study was carried out between the LSC modules and some building integrated photovoltaic technologies, using 1 kWh of electricity generation as a functional unit. LSC modules impacts were on average 870% lower than that of various PV technologies when compared on the basis of m2; the only exception concerned the comparison with CIS and a-Si technologies, where LSC modules impacts were about 150% higher in some categories (global warming potential, ozone layer depletion potential and photochemical oxidation potential). LSC modules had highest impacts in all categories (from 200% to 1900%) if compared with other PV technologies on the basis 1 kWh of energy generated. The results based on energy generation are easily interpretable considering the lower performance of LSC modules compared to other technologies; however, LSC modules show greater versatility and different possible applications due to the their transparency. The SW-LSC could represent an option for the future efficiency of the built environment: in this sense, even if the power output from LSC modules integrated into the window is limited, it is sufficient to cover the energy demand of an efficient system of Venetian blinds that allow regulating the internal loads autonomously and independently, with a consequent energy saving. Furthermore, thanks to the thermal characteristics of the frame and the regulation of the light inside the environment, the SW-LSC represents an element designed to improve thermal and lighting comfort inside buildings.

APA, Harvard, Vancouver, ISO, and other styles

26

Griffo, Michael S. "Charge dynamics in polymer-nanoparticle blends for nonvolatile memory : Surface enhanced fluorescence of a semiconducting polymer; surface plasmon assisted luminescent solar concentrator waveguides /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Fang, Chun-Yu, and 方鈞宥. "Luminescent Solar Concentrators Using Slanted Grating Structures." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/24071113260606861780.

Full text

Abstract:

碩士
國立中興大學
機械工程學系所
102
This study uses slanted grating structures to fabricate the luminescent solar concentrator (LSC) which is designed for guiding the incident light to the optical receiver in a specific direction and reducing the solar cell area. By coating the waveguide bottom with the fluorescent dyes, the LSC can convert specific wavelengths of light into the wavelengths of solar cell absorbing band. It will be expected to efficiently enhance the waveguide efficiency of LSCs and apply this device to the building-integrated photovoltaics. With the use of optical ray tracing software (ZEMAX), the sunlight passing through the waveguide with grating structures was simulated at the mixed sequential and non-sequential modes. According to the behaviors and paths of light guiding in the waveguide, the grating period for generating the total internal reflection was obtained. Based on the period, the diffraction efficiencies of the slanted grating were simulated by using the grating analysis software (G-solver). The grating’s parameters which can make a maximum efficiency difference between the positive first diffraction order and the negative first diffraction order were also discussed. Because the simulated grating period is too small, it is difficult to be fabricated by general equipments. Thus, the experiment was focused on the fabrication of slanted gratings of the thicker line width. The element fabrication of this study was focused on fabricating slanted gratings with the period of 4 μ m. The quartz glass and ITO glass were adopted as waveguide materials to conduct the photolithography process. Then, the inductively coupled plasma reactive ion etching (ICP-RIE) was used for etching the waveguide. Referring to many papers, different process parameters, like process pressure, electrode power, gas type, and gas flow rate, were tried. By making discussions and improvement after every experiment result, the purpose of fabricating slanted gratings has been achieved. Finally, the diffraction efficiencies of the fabricated grating elements were measured under positive first order, zero order, and negative first order. They were compared with the simulation results. When the wavelength of the light was 532nm and the depth of the slanted grating was 1500nm, the efficiency of positive first order was 4.6% and the efficiency of negative first order was 2.3%. The results were close to the simulation. Besides, the spectrum change of the light after passing through the slanted grating with fluorescent dyes was measured to verify whether the device can reduce the area of solar concentrator and enhance the efficiency or not.

APA, Harvard, Vancouver, ISO, and other styles

28

Wu, Jyun-Hao, and 吳俊灝. "Luminescent Solar Concentrators Using Subwavelength-Structured Optical Discs." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/87856536876887067074.

Full text

Abstract:

碩士
國立中興大學
機械工程學系所
98
The purpose of this study is to use the subwavelength structure of optical discs and anti-reflection coating to improve the optical waveguide effect of the luminescent solar concentrator (LSC). It can be widely applied to transparent materials, such as the building-integrated photovoltaic (BIPV). Through the vector diffraction theory and simulation by the grating software, we analyzed the influence of the period and depth of the subwavelength-structured surface on the optical waveguide effect, for achieving more efficient use of incident light. The subwavelength-structured surface allows the incident light to be diffracted into high order diffraction beams. It will give rise to an increase of the optical waveguide effect of the whole system if the diffraction angle is greater than the critical angle of total internal reflection. However, different wavelengths of incident light will cause different diffraction angles. In considering the absorption and emission spectrum of luminescent material, we selected the appropriate period and depth of the structure that will increase the internal optical waveguide effect of the whole system. According to the experimental results, we have found that the LSC with the structured surface can increase the optical waveguide effect of the substrate edge within 1~5% corresponding to different wavelengths. In the end of the study, the surface of the LSC was coated with the anti-reflection film, which is suitable in the range of absorption spectrum of the luminescent layer. The reflectivity of the substrate surface presents a reduction of 4~5%, that enhances the efficiency of the luminescent emission and increases the optical waveguide effect of the substrate edge. The experimental result shows that antireflection coating on the surface of an optical substrate can further enhance the optical waveguide effect by 0.5%.

APA, Harvard, Vancouver, ISO, and other styles

29

Li, Kai, and 李愷. "Highly Luminescent Gold Nanocluster Aluminosilicate Glasses for Low-loss Luminescent Solar Concentrators." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/ww8ukb.

Full text

Abstract:

碩士
中原大學
奈米科技碩士學位學程
107
This paper explores the use of Gold nanoclusters (AuNCs) in order to synthesize highly fluorescent organic/inorganic glass composites and further employ them to fabricate Luminescent Solar Concentrators (LSCs). Due to the large Stokes shift, AuNCs can reduce reabsorption losses and be developed to form environmental friendly and no-reabsorption LSC. The LSCs based on AuNCs can be used to enhance photon conversion efficiency by increasing the photons irradiated on the surface of the solar cell. However, in practical applications, there are still some problems to be solved such as solid-state quantum yield (QY), scattering, reabsorption loss, water resistance and outdoor stability. In this paper, highly luminescent AuNCs were prepared via simple synthetic route and further combined with waterproof aluminum silicate glass polymer. The study found that AuNCs organic/inorganic glass composites with high-loading (~14 wt％) exhibited a unique absorption curve, near-uniform absorption in the absorption range and near no-reabsorption (negligible) in the fluorescent divergent band. In addition, this material can enhance QY without sacrificing the original Stokes shift and optical transparency, opposite from the frequently used physicochemical properties of AuNCs with Aggregation-Enhanced Emission (AIE). Furthermore, the eco-friendly LSC based on AuNCs organic/inorganic glass composites has high outdoor stability and excellent water resistance.

APA, Harvard, Vancouver, ISO, and other styles

30

Frias, Ana Rita da Silva Rocha. "High performance luminescent solar concentrators for flexible waveguiding photovoltaics." Doctoral thesis, 2019. http://hdl.handle.net/10773/29231.

Full text

Abstract:

The mismatch between the AM1.5G spectrum and photovoltaic cell absorption is one of the critical factors limiting their performance. To overcome it, several approaches have been proposed. Among them, emphasis is given to luminescent down-shifting layers, additive devices that are able to enhance performance under typical operation conditions, and to luminescent solar concentrators, a complementary technology to PV cells for use in urban environments. Luminescent down-shifting layers are coatings that are directly deposited on the surface of photovoltaic cells, and absorb the incident radiation that is not absorbed by photovoltaic cells, subsequently re-emitting it at a specific wavelength and refracting/reflecting it towards the photovoltaic cell. Luminescent solar concentrators are devices comprising a transparent matrix incorporating optically active centres that absorb the incident radiation, which is then re-emitted at a specific wavelength and transferred by total internal reflection to photovoltaic cells located at the edges of the matrix. This configuration enables photovoltaic devices to be embedded in building facades or windows, allowing them to be transformed into energy harvesting units, contributing for the development of zero-energy buildings. This thesis aimed to produce and characterize transparent organic- inorganic hybrids with controlled thickness and refractive index using poly(methyl methacrylate), di- and triureasils incorporating different lanthanide ions, namely Tb3+, Eu3+, Y b3+ and Nd3+, and the fol- lowing organic dyes: Rhodamine 6G and Rhodamine 800, silicon 2,3- naphthalocyaninebis(trihexylsilyloxide), chlorophyll and R- phycoerythrin molecules with emission tuned from the visible to NIR spectral regions. LSCs with planar and cylindrical geometry are studied. The use of the cylindrical geometry allows the effect of concentration to be higher when compared with the planar geometry, since the ratio between the exposed area and the area of the edges is increased. The cylindrical geometry concentrators are produced from plastic optical fibres with hollow cores, where the optically active layer was injected. The exposed area was further optimised through the production of bundles of LSCs, in which optical fibres with different cladding geometries were placed side by side. Finally, the attractive properties of natural-based dye molecules for the production of luminescent solar concentrators, which have been poorly explored, are also studied through the incorporation of chlorophyll and R- phycoerythrin as optically active centres. Key experimental results were also validated using Monte-Carlo ray-tracing simulations.
O desfasamento entre o espetro AM1.5G e o espetro de absorção das células fotovoltaicas é um fator crítico que limita o desempenho das mesmas. De forma a ultrapassar isto, diversas aproximações têm sido propostas. Entre elas, têm sido enfatizadas as camadas luminescentes por desvio descendente de energia, dispositivos capazes de melhorar o desempenho em condições de operação específicas, e os concentradores solares luminescentes, considerados uma tecnologia complementar a das células fotovoltaicas para utilização em ambientes urbanos. As camadas luminescentes por desvio descendente de energia são revestimentos diretamente depositados no topo de células fotovoltaicas capazes de absorver a radiação incidente complementar à que as células fotovoltaicas absorvem e subsequentemente reemitem-na com um comprimento de onda específico que é refratado/refletido até à célula fotovoltaica. Os concentradores solares são dispositivos compostos por uma matriz transparente incorporando centros óticos ativos que absorbem a radiação incidente, que é posteriormente reemitida com um comprimento de onda específico e transportada por reflexão interna total até à célula fotovoltaica localizada nas extremidades da matriz. Esta configuração permite a produção de dispositivos fotovoltaicos embebidos em fachadas de edifícios e janelas, permitindo que estes sejam transformados em unidades de produção de energia, contribuindo para o desenvolvimento de edifícios de energia zero. O principal objetivo deste trabalho consiste no fabrico e caracterização de híbridos orgânicos-inorgânicos com espessura e índice de refração controlados utilizando polimetil-metacrilato, di- e tri-ureasil incorporando diferentes iões lantanídeos, nomeadamente Tb3+, Eu3+, Yb3+ and Nd3+, e corantes orgânicos como Rodamina 6G, Rodamina 800, Silício 2,3-naftalocianina bis(trietil siloxano), clorofila e R-ficoeritrina cuja emissão varia entre o visível e o infravermelho próximo. Concentradores solares luminescentes com geometria planares e cilíndrica foram estudados. A geometria cilíndrica permite que o efeito de concentração seja superior, quando comparado com a geometria planar, uma vez que a razão entre a área exposta e a área das extremidades aumenta. A geometria cilíndrica é explorada, através da produção de concentradores solares luminescentes em fibra ótica de plástico onde a camada ótica ativa se encontra no interior da fibra, como um preenchimento do núcleo oco. A possibilidade de aumentar a área exposta foi, também, abordada através do fabrico de uma matriz de concentradores solares luminescentes colocados lado a lado com diferentes geometrias da bainha. Para além disso, as propriedades óticas dos corantes orgânicos naturais, que têm sido pouco exploradas na literatura, foram alvo de estudo através da incorporação de moléculas de clorofila e de R-ficoeritrina como centros óticos em concentradores solares luminescentes. Os resultados experimentais mais relevantes foram validados através de simulações baseadas no método de Monte-Carlo.
Programa Doutoral em Física

APA, Harvard, Vancouver, ISO, and other styles

31

chao, Pin-jen, and 趙品仁. "Fluorescent simulation and experimental verification of luminescent solar concentrators." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/52702673315079021350.

Full text

Abstract:

碩士
國立中興大學
機械工程學系所
103
This thesis explores the characteristics of the fluorescence dye for luminescent solar concentrators (LSCs). This research discusses waveguide intensity by dye concentration change, superposition of different dyes, and LSCs with grating structures. This research applies the Monte Carlo method of the optical software, to simulate the characteristics of the fluorescence dye. Some experimental tests were verified in the research. The simulation items of waveguide intensity contain the dye concentration change, superposition of different dyes, and LSCs with grating structures. The effects of dye concentrations on the intensity of waveguide light of the LSC were investigated. Dyes of different colors have different ranges of absorption wavelength. They can increase the absorption range and the waveguide light intensity. Because of the diffraction effect from the grating, the LSC can produce different spectral effects according to the diffraction angles. The long wavelength of the incident light in the substrate is totally reflected while the short wavelength part is directly absorbed by the dye layer. Dyes can transform the portion of short wavelengths into that of long wavelengths. It makes the solar cell have better absorption. The experiments include the measurement of waveguide intensity with superposition of different dyes, LSCs with structures, and dyes mixed with UV (acrylic resin) and single dyes. The LSC with structures, which was fabricated by photo-lithography processes, used the photoresist as the structure. The experiments were compared with the simulations to verify the consistence between both results. The results of this study show that the experimental waveguide intensity curves are consistent with those of simulations. In the simulation of dye concentration change, the R6G fluorescent dye at high concentration does not enhance the waveguide intensity, which is similar to that in the Wu’s previous measurements.

APA, Harvard, Vancouver, ISO, and other styles

32

Carlos, Carlota Pereira de Almeida. "Advanced optical spectroscopy of new materials for luminescent solar concentrators." Master's thesis, 2019. http://hdl.handle.net/10773/29191.

Full text

Abstract:

The transition from the current energy matrix towards an environmentally friendly and a ordable energy sources is a crucial challenge of the 21st century. Fully energetically sustainable architecture is a strategic focus in this e ort, through the realisation of so-called net-zero energy buildings. This implies an increase in the use of renewable resources, such as the wind, tides and the sun. Hence, new technologies that integrate solar-harvesting devices into existing and newly constructed buildings are of growing relevance. Luminescent solar concentrators consist of a transparent matrix doped or coated with active optical centres that absorb the incident solar radiation, which is reemitted at a speci c wavelength and transferred by total internal re ection to the edges, where photovoltaic cells are located. This con guration enables photovoltaic devices to be embedded in building facades or windows, allowing them to be transformed into energy harvesting units. Challenges for the luminescent species in luminescent solar concentrators include the use of sustainable, natural-based organic molecules. In this scope, semitransparent amine-functionalized organic{inorganic hybrids (ureasils) incorporating two di erent natural-based organic dyes, chlorophyll and enhanced uorescent protein (eGFP), were synthesised and processed as thin lms and monoliths. The natural dyes' and organic-inorganic hybrid's excited state dynamics were studied and characterised { the absorption bands of chlorophyll a and eGFP were identi ed, as well as their characteristic emission in the red/NIR (600-750 nm) and visible (450-600 nm) spectral regions, respectively. The emission properties were further quanti ed through absolute emission quantum yield measurements, with the maximum values measured for the eGFP-doped di-ureasil hybrid (0:33 0:03) being two times higher than the maximum value found for the chlorophyll-doped hybrid samples (0:15 0:02). Fluorescent lifetime analysis was also performed resorting to two di erent techniques: time-correlated single photon counting and spectrally-resolved streak imaging, yielding uorescent emission lifetimes of 5 ns for chlorophyll and 2-3 ns for enhanced green uorescent protein, in solution and when incorporated into the hybrid hosts. Further analysis was carried out by tting a two exponential decay model to the uorescent decay curves of the for the green uorescent protein samples, considering that two distinct electronic states are responsible for the absorption around 488 nm and the emission at 510 nm. Based on the intriguing photoluminescent features of the dye-based samples, two prototypes of luminescent solar concentrators were fabricated and optically characterised. In particular, a liquid planar luminescent solar concentrator based on a glass container lled with eGFP dispersed in an aqueous solution and a eGFPdoped di-ureasil hybrid bulk planar luminescent solar concentrator. The devices were coupled to a silicon-based commercial PV device, revealing maximum optical conversion e ciencies of 2:99 0:01% (liquid) and 3:70 0:06% (bulk), illustrating the potential of this approach for the development of nature-based luminescent solar concentrators, meeting the requirements of reliable, sustainable and competitive energy systems.
A transição da matriz energética atual para fontes de energia competitivas de baixo impacto ambiental é uma problemática central no século XXI. A arquitetura energeticamente sustentável é um ponto estratégico nesse esforço, através da realização dos chamados edifícios de energia zero. Por defenição, estes edifícios fazem uso de sistemas de produção de energia renovável local, como por exemplo a fotovoltaica, para satisfazer as suas necessidades energéticas. Assim, novas tecnologias que integrem dispositivos de coleção de energia solar em edifícios existentes ou recémconstruídos são de crescente relevância. Os concentradores solares luminescentes são dispositivos compostos por uma matriz transparente com centros óticos ativos incorporados. Estes absorbem a radiação incidente, que é posteriormente reemitida com um comprimento de onda específico e transportada por reflexão interna total até à célula fotovoltaica localizada nas extremidades da matriz. Esta configuração permite a produção de dispositivos fotovoltaicos incorporados em fachadas de edifícios e janelas, permitindo que estes sejam transformados em unidades de produção de energia. Atualmente, um dos desafios na áreas dos concentradores solares luminescentes é a incorporação de moléculas orgânicas naturais como centros óticos. Neste âmbito, foram fabricados e processados híbridos orgânico-inorgânicos semitransparentes, denominados por ureiasils, modificados por dois corantes orgânicos naturais, clorofila e proteína verde fluorescente (eGFP). A dinâmica entre os estados excitados dos corantes naturais e da matriz híbrida foi estudada e caracterizada - foram identifícadas as bandas de absorção da clorofila a e da eGFP, assim como a sua emissão característica no vermelho/infravermelho próximo (600-750 nm) e na região do visível (450-600 nm), respetivamente. As propriedades de emissão foram quantificadas através de medidas de rendimento quântico absoluto, registando-se um valor máximo para o híbrido com eGFP incorporada (0,33+/-0,03) duas vezes superior ao encontrado para as matrizes híbridas dopadas com clorofila (0,15+/-0,02). Foram também analisados os tempos de vida dos emissão dos estados excitados das várias amostras, tendo sido encontrados valores ~5 ns para a clorofila e ~2-3 ns para a eGFP, em solução ou quando incorporadas nas matrizes híbridas. Procedeu-se ainda a uma análise mais aprofundada no caso das amostras com eGFP, através da aplicação de um modelo bi-exponencial às curvas de decaimento, uma vez que o modelo eletrónico da mesma indica a presença de dois estados excitados distintos responsáveis pela absorção em torno dos 488 nm e emissão a 510 nm. Devido às características fotoluminescentes interessantes das amostras à base de corantes naturais para aplicações em concentradores solares luminescentes, foram fabricados e caracterizados dois protótipos com geometria planar { um concentrador solar luminescente baseado num recipiente de vidro cheio com eGFP em solução aquosa, e um outro concentrador que consistia num monolito da matriz híbrida dopada com eGFP. Os dispositivos foram acoplados a uma célula fotovoltaica comercial de silício, revelando eficiências óticas de conversão máximas de 2; 99+/-0; 01% e 3; 70+/-0; 06%, respetivamente, ilustrando o potencial desta abordagem para o desenvolvimento de sistemas energéticos sustentáveis e competitivos.
Mestrado em Engenharia Física

APA, Harvard, Vancouver, ISO, and other styles

33

Sie, Yun-Rong, and 謝昀融. "Photophysical properties of gold nanoclusters for low-loss luminescent solar concentrators." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/56rdc4.

Full text

Abstract:

碩士
中原大學
物理研究所
107
A Luminescent Solar Concentrator (LSC) consists of a polymeric or glassy optical waveguide doped with highly emissive fluorophores. Following light absorption, LSC luminophores re-emit photons which are then guided to edges of the device, where solar cells are attached. Generally, the loading concentration of luminophores in LSC is strictly limited to reduce concentration-induced quenching (CIQ), reabsorption loss and aggregation-induced scattering (AIS). In order to solve the aforementioned problems, this research study utilized Gold Nanoclusters (GSH-AuNCs). GSH-AuNCs has large Stoke-shift and low reabsorption characteristics. GSH-AuNCs were dispersed in suitable Polyvinylpyrrolidone (PVP) polymer in order to prepare LSC with different concentration loading. Even at a high loading concentration of 26wt%, the quantum yield PL-QY is enhanced up to ~25% (only 1% in the pristine aqueous solution), thanks to the outstanding ligand-matrix effective inhibition of non-radiative recombination which enhanced the process of radiation recombination. In addition, the high concentration (~74wt%) of this research study still maintains good film uniformity and optical properties, without AIS effect, while maintaining minimal reabsorption and scattering. This phenomenon allowed the edge-emission efficiency to be maintained up to ~70% in numerical value. Furthermore, the external quantum yield is about 15% at 400 nm.

APA, Harvard, Vancouver, ISO, and other styles

34

Guo, Yu-Fang, and 郭宇芳. "Flexible Luminescent Solar Concentrators Using Photo-Stable, Heavy-Metal-Free Quantum Dots." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/65598722890095339822.

Full text

Abstract:

碩士
中原大學
物理研究所
104
Luminescent solar concentrators (LSCs) can be used to concentrate both diffuse and direct components of sunlight without the need of complex light tracking, thus can facilitate solar cells to efficiently harvest solar energy, while reducing the material cost of solar cells. Unfortunately, organic materials exhibit large re-absorption losses due to small Stokes shift, narrow absorption bands and poor photo-stability, thus significantly limit their practical uses in LSCs.　Heavy-metal-containing colloidal quantum dots (CQDs) with Stokes-shift engineering hold some unique properties, such as low reabsorption losses, stable PL emission and high PL quantum yields that are much beneficial for achieving high-performance LSCs but those luminophores are strongly toxic and involve complex manufacturing processes.　Here, we demonstrate flexible, photo-stable and semi-transparent LSCs based on facile-microwave-synthesis, heavy-metal-free CuInS２/ZnS CQDs (CIS/ZnS QDs) embedded in the PDMS waveguide matrix. Such flexible PDMS matrix not only can serve as a host waveguide but also can well disperse CIS/ZnS QDs from aggregation-induced PL quenching.　By changing the cation ratio of CIS/ZnS QDs, the Stokes-shift and photoluminescence quantum yields (PL-QY) can be engineered. The PL emission of those QDs exhibit large Stoke-shift, broad emission and absorption bands, and long PL lifetime due to defect-related emission processes. To access the performance of our flexible LSCs, excitation-position-dependent PL measurement were used to quantify the re-absorption losses in the flexible LSCs.

APA, Harvard, Vancouver, ISO, and other styles

35

Jiang, Zh-Cheng, and 姜智程. "Solution-processed, Eco-friendly Carbon Dots for Light-emitting Thin Films and Luminescent Solar Concentrators." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/45139329502181400760.

Full text

Abstract:

碩士
中原大學
物理研究所
104
Solution-processed carbon dots (CDs) have attracted much attention owing to their superior materials and photoluminescence (PL) properties, such as abundant precursor materials, less toxicity, high photo-stability and tunable emission. However, their PL properties, including PL quantum yields and photo-stability would be significantly degraded due to concentration-induced solid-state quenching and unstable surface. In this thesis, we fabricated high quality CDs/polyvinyl alcohol (PVA) light-emitting flexible films with submicron structure patterns by a facile and low cost method. PVA is chosen as the host matrix to both disperse and passivate CDs, leading to enhanced internal quantum yields (69%) in the solid states. Patterned CDs/PVA composite can be used to extract the trapped light, thus mitigate the waveguide-mode losses, approximately doubling the external light extraction efficiency. Such CDs/PVA composites also exhibit good photo-stability, and can be used as eco-friendly, low cost phosphors for solid-state lighting. On the other hand, those CDs can also be utilized as eco-friendly luminophores for promising applications in luminescent solar concentrators (LSCs). Such LSCs can be used to concentrate the solar light to enhance the efficiency and reduce the material costs of solar cells. We have fabricated flexible LCSs based on hydrophobic CDs doped PDMS waveguide and characterize their performances using spectroscopic methods. We found that those hydrophobic CDs can be uniformly dispersed into PDMS waveguide and exhibit good photo-stability. The key metric of LSCs, namely, reabsorption losses, has also been investigated using excitation-position-dependent PL spectroscopy. Our demonstration can pave a way to further design efficient LSCs based on eco-friendly CDs in the future.

APA, Harvard, Vancouver, ISO, and other styles

36

Chang, Li-Yun, and 張力云. "Investigation of photophysical properties of carbon quantum dots and their application in luminescent solar concentrators." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/vp7y56.

Full text

Abstract:

碩士
中原大學
物理研究所
106
Novel solar windows can be realized by integrating conventional solar cells and transparent luminescent solar concentrators (LSCs). Recently, efficient LSCs have been demonstrated based on colloidal quantum dots (CQDs) due to their unique photophysical properties. Unfortunately, most of matured CQDs contain toxic heavy-metal elements and need to be synthesized in the hazardous organic solvent. It would be beneficial to replace conventional heavy-metal CQDs with eco-friendly nano-materials, while preserving unique photophysical properties. Carbon nano-dots (CNDs) are newly emerged luminescent nano-materials that can be simply synthesized using hydrothermal method based on cost-effective, earth-abundant precursors. The main challenge for CNDs utilized in the solid state is concentration-induced self-quenching, thus need to be addressed for the LSC applications. 　　In this thesis, the effect of solid matrices on the photophysical properties of CNDs were investigated, which is necessary for preparing efficient LSCs. We found that the excited-state dynamics can be modified by the solid matrices, thus influencing the PL quantum yields (PL-QYs). In addition, the uniformity of solid-state thin films can be also affected by the solid matrices. We also demonstrated that the CNDs can be uniformly dispersed in a PVA solid matrix and hold high solid-stat PL-QYs up to ~50%. Motivated by such fascinating properties, greener LSCs with a geometric gain of ~ 10 were fabricated based on CNDs/PVA nano-composites, which exhibit internal quantum efficiency of 30% and stable PL emission.

APA, Harvard, Vancouver, ISO, and other styles

37

Cai, Kun-Bin, and 蔡錕斌. "Investigation of photophysical properties of greener gold nanoclusters and their applications in luminescent solar concentrators." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/59me6s.

Full text

Abstract:

碩士
中原大學
物理研究所
106
A luminescent solar concentrator (LSC) can be used to concentrate both direct and diffused sunlight, which is the main component of solar windows. Recently, efficient LSCs based on heavy-metal colloidal quantum dots (CQDs) with carefully designed heterostructures have been demonstrated. Unfortunately, those CQDs involve toxic elements and need to be synthesized in the hazardous organic solvent. In addition, they still suffer from reabsorption losses and solid-state concentration-induced quenching, which need to be addressed for realizing large-area greener LSCs. Eco-friendly gold nanoclusters (AuNCs), which can be directly synthesized in an aqueous solution have attracted our attention due to their unique PL emission for LSC applications. The PL emission of GSH-AuNCs hold large Stokes shift, which would be beneficial for reducing the reabsorption losses in LSCs, however, the extremely low PL quantum yields (PL-QYs) significantly hinder their performance in LSCs. In this thesis, the photophysical properties were investigated for Zn2+-induced cross-linked GSH-AuNCs (Zn-GSH-AuNCs) in solution and in the solid state. We found that the Zn-GSH-AuNCs at pH 4 exhibit enhanced PL-QYs of ~7% and enlarged Stokes shifts as compared with that of as-synthesized GSH-AuNCs (PL-QY~0.4%). More importantly, Zn-GSH-AuNCs embedded in a rigid polymer matrix hold extremely high solid-state PL-QYs up to ~53% along with blue-shifted PL spectrum due to suppression of non-radiative relaxation and switching of the emissive triplet states. Owing to appealing photophysical properties, greener LSCs were fabricated based on those Zn-GSH-AuNCs. The LSCs exhibit high internal quantum efficiency of ~33% thanks to low reabsorption losses and high solid-sate PL-QYs, which is already comparable with that of the LSCs based on conventional toxic CQDs.

APA, Harvard, Vancouver, ISO, and other styles

38

WU, Yao-Hsuan, and 巫耀玄. "Studies of photophysical properties of solid-state carbon nano-dot thin films for greener luminescent solar concentrators." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/nx66pf.

Full text

Abstract:

碩士
中原大學
奈米科技碩士學位學程
106
A luminescent solar concentrator (LSC) is consisted of the luminophores and a waveguide that can be used to spatially concentrate both direct and diffused sunlight without the need of complex and expensive solar-tracking and cooling systems. Recently, colloidal quantum dots (CQDs) with some unique photophysical properties have attracted much attention as the luminophores in LSCs. However, most of mature CQDs contain heavy metals and need to be synthesized in the hazardous organic solvent. In addition, they also suffered from concentration-induced quenching (CIQ), thus the loading concentration of luminophores doped in LSCs is restricted. Unfortunately, this would reduce the light-absorbing efficiency, leading to large transmission losses. To address all the issues mentioned previously, organosilane-functionalized carbon nanodots (Si-CNDs) were synthesized based on cost-effective, earth-abundant precursors using a simple hydrothermal method. Such Si-CNDs exhibit some unique photophysical properties, including large absorption coefficient, high PL quantum yields (PL-QYs) and resistance to CIQ effect. Due to good film-forming properties, greener LSCs with different loading concentrations can be simply fabricated by directly cross-linking Si-CNDs on the glass waveguide. The LSCs are highly transparent even under high loading concentration up to 75 wt%, indicating high uniformity of Si-CND distribution. The LSCs with 25 wt% loading contents still possess high solid-state PL-QYs up to ~41% upon the calibration of reabsorption losses and high internal quantum efficiency of ~23% due to low scattering losses. We expect our demonstration can pave a way to further design efficient greener LSCs after further reducing the reabsorption losses.

APA, Harvard, Vancouver, ISO, and other styles

39

Cardoso, Marita Alves. "Luminescent organic-inorganic hybrid electrolytes for smart building glazing." Doctoral thesis, 2021. http://hdl.handle.net/10773/31524.

Full text

Abstract:

There is a global need to improve the building energy generation efficiency in the new generation of buildings, so called zero-energy buildings (ZEBs). One strategy includes the development of smart windows based on electrochromic devices (ECDs) coupled to luminescent layers and luminescent solar concentrators (LSCs). New materials based on lanthanide complexes with high quantum efficiency incorporated in appropriate host matrices prepared by solgel chemistry opens challenging opportunities for the development of new devices with remarkable electro-optical performance and foreseen application as smart windows for ZEBs. In this thesis, new electrolytes based on organicinorganic hybrids doped with an ionic liquid allowed the production of ECDs with high visible and NIR transparency and voltage-actuated dual coloration tuning, enabling three-mode operation (bright hot, semi-bright warm, and dark cold). The ECD delivers a number of extraordinary features, in particular high switching efficiency and optical modulation, good cycling stability, large coloration efficiency, excellent optical memory, and unusual self-healing ability following mechanical stress. In addition, new lanthanide ions (Ln3+ = Nd3+, Eu3+, Tb3+, Yb3+)-doped surface functionalized ionosilicas (ISs) were produced, characterized and embedded in poly(methyl methacrylate) yielding transparent films with negligible self-absorption with potential to be used LDS layers, and LSC into a single device. The significant absolute increase observed in the PV cell external quantum efficiency (EQE~32% between 300-360 nm relatively to the bare PV cell) supports the applicability of the developed materials for ZEBs.
Existe uma necessidade global de melhorar a eficiência energética nos edifícios com vista a uma nova geração de edifícios denominados edifícios de balanço energético nulo (ZEBs). Uma das estratégias propostas inclui o desenvolvimento de janelas inteligentes baseadas em dispositivos eletrocrómicos (ECDs) acoplados a camadas luminescentes e concentradores solares luminescentes (LSCs). Novos materiais baseados em complexos de iões lantanídeos com elevado rendimento quântico de emissão incorporados em matrizes hospedeiras apropriadas, preparadas pelo método sol-gel, abrem um leque de oportunidades para o desenvolvimento de novos dispositivos com notável desempenho eletro-ótico para janelas de ZEBs. Nesta tese, novos eletrólitos baseados em híbridos orgânicos-inorgânicos dopados com um líquido iónico luminescente permitiram a produção de ECDs com elevada transparência nas regiões espetrais do visível e NIR e, possibilitando o ajuste fino da passagem de luz solar e da energia solar, permitindo operação em três modos (brilhante quente, semi-brilhante quente, e frio escuro). O ECD oferece uma série de recursos extraordinários, em particular alta eficiência e modulação ótica, boa estabilidade, grande eficiência de coloração, excelente memória ótica e capacidade de auto-regeneração após stress mecânico. Além disso, novas ionossílicas funcionalizadas na superfície dopadas com iões lantanídeos (Ln3+ = Nd3+, Eu3+, Tb3+,Yb3+) foram produzidas, caracterizadas e incorporadas em poli(metil metacrilato) produzindo filmes transparentes com auto-absorção desprezável com potencial aplicação em LDS e LSC. Foi observado um aumento absoluto significativo na eficiência quântica externa da célula PV (EQE ~ 32% entre 300-360 nm em relação à célula PV base) demostrando a aplicabilidade dos materiais desenvolvidos para ZEBs.
Programa Doutoral em Ciência e Engenharia de Materiais

APA, Harvard, Vancouver, ISO, and other styles

40

Taddei, Maria. "Transient absorption spectroscopy: a fundamental tool for progress in medical therapies, renewable energies and electronic devices." Doctoral thesis, 2022. http://hdl.handle.net/2158/1275273.

Full text

Abstract:

In this work, we used transient absorption spectroscopy to study three different light sensitive systems: Triplet Photosensitizers, Luminescent Solar Concentrators and Molecular Photoswitches. In all these systems, unwanted transient states can drastically reduce the rate of the following exploitable photophysical transformation. Our attention was devoted to understand the reaction mechanisms of the photoinduced processes, in order to gather information about the possible ways to improve their yield.

APA, Harvard, Vancouver, ISO, and other styles

41

Almeida, Mário André Madeira de. "Photoluminescent properties of doped alkali borosilicate glasses." Master's thesis, 2017. http://hdl.handle.net/10362/34212.

Full text

Abstract:

This project was developed with the purpose to achieve innovative solutions of UV light down conversion. Such was accomplished through the synthesis of photoluminescent glasses doped with tin oxide and copper oxide, also preliminary studies on the development of photoluminescent thin films based on the same elements was approached. Photoluminescent quantum yields and Stokes shift were taken as guidelines to evaluate the photoluminescent behaviour of the produced samples. The synthetic strategy applied for photoluminescent glass samples was systematic, it consisted on the insertion of a variable doping amount of each element over an alumina-borosilicate glass matrix which were prepared at high temperatures of 1400 ºC and 1550 ºC. Structural features were evaluated through SSNMR for 29Si, 11B, 23Na, and Raman spectroscopy, which showed that doping does not affect the network structural matrix. Dilatometry measurements were performed showing a negligible variation of the thermomechanical properties of the samples. Doping concentrations have revealed to be a key factor for the achievement of high quantum performances, where we have observed triplet state light emission derived from three emissive species. Its origin resides in Sn2+, Sn2+ aggregates and Cu+ species in the glass matrix. Tin oxide doped samples shown quantum efficiencies of 50% and 1.7 eV Stokes shift for 1.4% molar tin oxide concentration, while copper oxide doped samples present 58% quantum efficiency and large 3 eV Stokes shift for 0.14% molar concentration. Thin film deposition strategy was based on the identification of optimal conditions for the formation of copper and tin oxide crystalline phases. Results were evaluated through X-ray diffraction and Raman spectroscopy showing the formation of both crystalline phases over variable oxygen flow. A multi-layer thin film deposition was performed and diffusion was attempted through thermal treatment. Results indicate the formation of a protective SnO2 layer over the formation of Cu2O phase, increasing its thermal stability to 400 ºC.

APA, Harvard, Vancouver, ISO, and other styles

42

Araújo, Joana Carolina Carvalho de. "Desenvolvimento de materiais híbridos orgânicos-inorgânicos para aplicação em revestimentos de base polimérica." Master's thesis, 2018. http://hdl.handle.net/1822/65074.

Full text

Abstract:

Dissertação de mestrado em Técnicas de Caracterização e Análise Química
A energia é possivelmente um dos maiores desafios que a União Europeia terá de enfrentar nas próximas décadas, sendo necessário implementar estratégias para a utilização mais eficiente dos recursos energéticos nos edifícios, como por exemplo através da climatização inteligente dos edifícios (arrefecimento e aquecimento passivos) ou da conversão da energia solar em eletricidade. Neste trabalho é descrito o desenvolvimento de revestimentos poliméricos funcionalizados com óxidos metálicos e iões de terras raras, que potenciam a conversão da energia solar em eletricidade e a climatização eficiente dos edifícios através da sua integração em janelas inteligentes. Estes sistemas de concentração e conversão de energia solar, baseados em materiais luminescentes, são designados por LSC’s (Concentradores Solares Luminescentes). O estudo centrou-se na síntese de nanopartículas ocas de sílica pelo método de sol-gel, funcionalização destas com Eu3+ ou Nd3+:Yb3+ e posterior incorporação em filmes poliméricos, otimizados para aplicação em substratos de vidro. Ao longo do trabalho efetuou-se a caracterização morfológica, química e térmica dos materiais desenvolvidos, recorrendo às técnicas de SEM-EDS, STEM, DLS, XRD, FTIR, espetroscopia de UV-Vis, UV-Vis NIR e de fluorescência e TGA. A avaliação de desempenho dos protótipos de LSC’s construídos foi efetuada com base na determinação da eficiência de conversão energética, e na monitorização das propriedades de barreira térmica do revestimento polimérico aditivado com as sílicas. Obtiveram-se revestimentos transparentes (transmitância > 90% na região do visível do espetro solar), com um excelente efeito de barreira térmica (em alguns casos capazes de produzir um abaixamento térmico até 10 °C). No geral, desenvolveram-se com sucesso materiais funcionais, para aplicações em janelas inteligentes, nomeadamente revestimentos poliméricos de elevada transmitância, em substratos de vidro, com dupla funcionalidade: barreira térmica e concentração/conversão energética.
The energy used in European buildings plays a big part of the world’s energy consumption. Therefore, strategies for a more intelligent use of the energy resources, as smart climatization of the buildings (passive heating and cooling), need to be implemented. This work, describes the development of polymeric coatings, functionalized with metallic oxides and rare-earth ions, for the conversion of solar energy into electricity and smart climatization of buildings, through the integration of these materials in smart windows. These systems of concentration and conversion of solar energy, based in luminescent materials, are called LSC’s (Luminescent Solar Concentrators). Hollow silica nanospheres were synthesized by the sol-gel method and functionalized with Eu and the pair Nd3+:Yb3+, then they were incorporated into polymeric films and deposited in glass substrates. A morphological, chemical and thermal characterization was made, using various techniques, as SEM-EDS, STEM, DLS, XRD, FTIR, UV-Vis, UV-Vis NIR and fluorescence spectroscopy and TGA. LSC prototypes were built and characterized, to assess its thermal performance and its energy conversion efficiency, using a solar simulator. Experimental results show that functionalized hollow silica nanospheres, with 200 nm, were obtained. Transparent coatings, with an excellent thermal barrier effect (in some cases able to the reduce the temperature by 10 °C) were also obtained. The built prototypes showed good results of photon-to-current energy conversion efficiency. Overall, functional materials for application in smart windows, in particular high transmittance polymeric coatings in glass substrates, with dual functionality (thermal barrier and energy concentration/conversion) were successfully developed.
Ao CeNTI pela oportunidade de realização deste estágio e pelo fornecimento de todos os meios necessários, inclusive pela possibilidade de desenvolver o trabalho no contexto do projeto WINNER – Smart windows for zero carbon energy buildings, financiado pelo programa ERA-NET LAC (América Latina, Caribe e União Europeia, ELAC2014/ESE-0146), e pelo Ministério da Ciência, Tecnologia e Ensino Superior via FCT - Fundação Nacional Portuguesa para Ciência e Tecnologia (Ref. ERANETLAC/0007/2014), ao qual também agradeço o financiamento.

APA, Harvard, Vancouver, ISO, and other styles

43

Hsieh, You-Yang, and 謝佑陽. "Stable Luminescent Carbon-Nanodot Gel Glasses for Eco-Friendly Luminescent Solar Concentrator." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/xxt77c.

Full text

Abstract:

碩士
中原大學
物理研究所
107
Luminescent Solar Concentrators, (LSCs) are composed of loaded luminophores and glass waveguides designed to efficiently harvest both incident and diffused solar irradiation devoid of complex solar tracking system. However, most of reported LSCs bank on on colloidal fluorescent materials with noble photophysical properties are frequently comprised of heavy metals and toxic organic solvents. In lieu of this, it is necessary to search for nanomaterials with excellent photo physical, yet considered to cause minimal harm to environment and human health. Carbon Dots (CDs) are environmental friendly nanomaterials but suffers from minimal problems such as concentration-induced quenching (CIQ) and aggregation-induced scattering (AIS). At the same time, the polymer materials used in LSC today have disadvantages such as long-term UV irradiation or heating, which will destroy the photophysical properties and easily hydrolyze the samples after moisture absorption.Therefore, in this study, sulfonated alkyl polymers with excellent heat resistance and stability were bonded to carbon quantum dots, and silanes (-NH2, -NCO, -CH3) with different functional groups, and were selected to react with carbon quantum dots to further explore their light-harvesting properties. The photophysical properties of the CDs used in this research was investigated in order to find the best and optimized conditions for further utilization as a luminescent solar concentrator.

APA, Harvard, Vancouver, ISO, and other styles

44

Chou, Jyun-Chung, and 周俊忠. "Study of dye characteristics for the luminescent solar concentrator." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/48214719788095271785.

Full text

Abstract:

碩士
國立中興大學
機械工程學系所
102
Previous studies had proposed systematic structures for tandem luminescent solar concentrators (LSCs). However, as the use of two or more waveguide plates in combination with dyes is required, they are different from typical LSCs that put a single kind of dye over a single-layered waveguide. In order to simplify the tandem LSCs to be the single-layered configuration, this study proposed the color mixing from two of the three dyes in colors of red, orange, and green to make the mixing dyes of red-orange, orange-green, and red-green colors. They were then coated on the waveguide to form the dye-mixing LSCs for observing the effect of extending the spectral range of radiation. Besides, this study compared the waveguide strength between the single-layered dye-mixing LSCs and the double-layered single-dye LSCs. With the CCD spectrometer, the measurement results show that the dye characteristics of double-layered single-dye LSCs allow more extension of the spectral range of radiation. Furthermore, this study coated three dyes in colors of red, orange, and green to the waveguide plates with different thicknesses of the same material as well as the waveguide plates with the same thickness of different materials to conduct experimental measurements and observe the dye characteristics. The experimental results show that thicker waveguide plates provide higher light intensities from waveguides. The waveguide plates made of the plastic material can obtain better light intensities than those made of the glass material.

APA, Harvard, Vancouver, ISO, and other styles

45

Chen, Yuan-Yu, and 陳垣佑. "Study of light guiding characteristics for the luminescent solar concentrator with grating structures." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/53171371830711971062.

Full text

Abstract:

碩士
國立中興大學
機械工程學系所
102
This study is the extension of the previous study of my laboratory colleague Jyun-Hao Wu. It is mainly about fabricating the sub-wavelength structure of a disc on glass for luminescent solar concentrators (LSCs). This fabrication would be more close to the real application of building-integrated photovoltaics (BIPV). Because of the sunrise and sunset phenomena, the incident angle of light is an important factor. After finding the optimal incident angle, the LSC can be designed according to the position of building materials where the sunlight can reach the most. In order to promote the efficiency of light guiding, some steps were taken in the experiment. First, the grating structure was made on glass. The ideal grating period was calculated to be 600nm by utilizing the grating diffraction equation and total reflection equation. Second, the light path was simulated and verified by using the ray-tracing software Zemax. The function of the grating structure was to split light according to different wavelengths. The ideal grating can lead shorter wavelengths of light, which will be absorbed by fluorescent dye, to the fluorescent dye layer and let longer wavelengths of light, which will not be absorbed by fluorescent dye, totally internal-reflected in the substrate. Then, the grating simulation software GSolver was adopted to simulate the diffraction efficiencies of different gratings. When light enters the grating structure, it would be diffracted into several diffraction orders. The diffractive efficiency of each order would change at different incident angles. The diffractive efficiencies in different incident conditions were simulated by GSolver. Using Fresnel equations, the transmittance and reflectance of diffraction light on the bottom layer of the substrate were obtained. By multiplying the transmittance and diffractive efficiency, the percentage of light, which enters the dye layer, can be known. In the experiment, the gratings with periods of 10μm and 4μm were fabricated by the technologies of photolithography and etching processes, respectively. The spin coater was then applied to coat the R6G fluorescent dye on the substrate. After finishing the device fabrication, the spectrometer was used to measure the waveguide effect. When the incident angle is small, there is high efficiency for the grating with the period of 600nm. However, as the incident angle is higher than 20°, the efficiency drops. It is the reason that the large diffraction angle makes the light unable to reach the dye layer. The grating with the period of 10μm has better efficiency at the angles of 50°~60° and similar for 4μm at the angle of 40°. The thickness of fluorescent dye can also affect the waveguide efficiency. The thickness of 2924nm raises 2.51% of efficiency when compared with that of 2059nm.

APA, Harvard, Vancouver, ISO, and other styles

46

陳品竹, Pin-Chu Chen, and 陳品竹. "Slanted Grating Manufacturing for the Luminescent Solar Concentrator Using the Canted Exposure Method." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/77614422729628900124.

Full text

Abstract:

碩士
國立中興大學
機械工程學系所
104
This research was focused on the optical efficiency improvement of the luminescent solar concentrator (LSC). This research combines the slanted grating with the design of the LSC. By adjusting the structure, period, and depth, the incident light can be diffracted into specific orders. It could have the purposes of increasing the transfer efficiency of fluorescent dyes and reducing the area of solar cell usage. First, the diffraction equation was applied to the calculation of both the critical angle for total reflection and the grating period for diffraction in the waveguide. Then, the granting simulation software, Gsolver, was used to analyze the granting structures with different shapes. By investigating the diffraction efficiencies among different orders for grating parameters, the optimal grating design values could be found. In the experiment, the slanted gratings with periods of 4 µm and 6 µm, which have the duty cycle of 50%, were fabricated by the canted exposure method. The photoresist was used as the grating structures. After the lithographic process, the devices were measured for the light intensities of all diffraction orders. Furthermore, different process parameters were tested for comparing the measured results with those of the optical simulation and verifying the feasibility of the manufacturing. Finally, the slanted grating was glued with the fluorescent dye by UV glue for fabricating a compact LSC. In order to verify the design feasibility, waveguide effects were measured and compared with samples of various parameters.

APA, Harvard, Vancouver, ISO, and other styles

47

Chiang, Yi-Ting, and 江宜庭. "Novel Synthesis of Perovskite Nanocrystals for Applications in Luminescent Solar Concentrator and Photocatalysis." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/p5arqh.

Full text

Abstract:

碩士
國立交通大學
應用化學系分子科學碩博士班
107
In this thesis, we have devolped a robust hot-addition method (HAM) inspired by the hot injection method. HAM can solve the problem that the organic cation is easily decomposed at high temperature which cause difficulty for synthesizing the organic-inorganic hybrid perovskite nanocrystals. The HAM can synthesize highly crystalline and stable organic-inorganic perovskite nanocrystal with great photoluminescent quantum yield and tunable optical properties. The MAPbBr3 and CsFAPbBr3 were successfully synthesized by the hot addition method, which proved that the HAM is applicable to various organic cations. The effects of different A cations and different synthetic processes on the optical properties of perovskite nanocrystals were investigated by following perovskite nanocrystals. CsPbBr3 was prepared by hot injection method. CsFAPbBr3 was generated by combining hot injection method and HAM. MAPbBr3 was synthesized by three different synthesis methods. The photocatalysis reactions chosen under solid-gas phase reaction conditions were carried out under blue LED light. Then, the differences in optical properties were used to explain the photocatalysis performance of different perovskite nanocrystals. Since MAPbBr3 photoluminescence lifetime is longer which let excited electrons can easily transmit for reduction reaction, MAPbBr3 has better performance than other component lead halide perovskites. Among the three types MAPbBr3, the MAPbBr3 synthesized by the participation of trace water in the reaction show superior catalytic activity and stability. In addition, MAPbCl3 and Mn-doped MAPbCl3 (Mn: MAPbCl3) were prepared by HAM for the development of luminescent solar concentrator (LSC) applications. The Mn:MAPbCl3 perovskite nanocrystals show a remarkable Stokes shift up to 200 nm. Based on this property, solar concentrators had fabricated with MAPbCl3 and Mn:MAPbCl3 as the luminescent medium. The device still retain a certain transmittance while exhibiting high optical efficiencies of 1.2% and 3.3%, respectively. However, efficiency of LSC remained unaffected after enlargment of LSC device because high stoke shift (200nm) achieved by Mn doping supresses re-absorption of emitted photon.

APA, Harvard, Vancouver, ISO, and other styles

48

Pinheiro, Ana Catarina Tavares. "Luminescent Glass Materials for Photovoltaics." Master's thesis, 2019. http://hdl.handle.net/10362/89660.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

MUPPARAPU, RAJESHKUMAR. "Absorption Enhancement by Light Scattering for Solar Energy Applications." Doctoral thesis, 2013. http://hdl.handle.net/2158/796858.

Full text

Abstract:

In this thesis, I discuss few novel approaches to enhance the light-matter interaction, which have applications in solar energy. Enhancement of absorption/ fluorescence is a topic of immense interest in recent years for its importance in various fields: bio-sensing and diagnostics, solar energy, imaging, forensics, etc.. Often, applications involving fluorescence are quite low efficient, and which is mainly attributed to poor fluorescence from constituent fluorescent molecules. Enhancing fluorescence of molecules can enable to realize very efficient applications. And, one such application which needs attention is Luminescent solar concentrator, which is a main topic of discussion in this thesis. Luminescent solar concentrators (LSCs) are polymer slabs filled with fluorescent molecules which absorb incoming sunlight and emit fluorescence inside the slab, and which is partially guided to the edges where photovoltaic cells are attached. Poor absorption/fluorescence of organic molecules is due to their intrinsic chemical structure, due to which either they display huge non-radiative decay losses or poor absorption efficiency, etc.. It is well know that the amount of light emitted by molecules also depends on their surrounding medium properties. Modifying the surrounding environment very close to the molecules can actually modify the intrinsic fluorescence properties of molecules. This idea has been applied quite a lot to modify the properties of molecules close to metallic nanostructures/nanoparticles. When it comes to enhance the fluorescence of molecules embedded in polymer slabs like LSCs all existing approaches fail to work. In thesis, I discuss elaborately, in particular answering following questions: why existing approaches fail to work, essentially what kind of approaches are needed, and how they should be implemented.

APA, Harvard, Vancouver, ISO, and other styles

50

YU, WEI-GWO, and 于偉國. "Optical Properties Analysis of Silicon Membrane Doped Oxide Microparticles and Application to Inorganic Phosphor luminescent solar concentrator." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/k8cvdy.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Luminescent Solar Concentrators'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles