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Relevant bibliographies by topics / Exciton diffusion length

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Academic literature on the topic 'Exciton diffusion length'

Author: Grafiati

Published: 4 June 2021

Last updated: 2 November 2024

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Journal articles on the topic "Exciton diffusion length"

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Lincoln, Craig N., Matthias Block, Bastian Baudisch, Pavel Malevich, Hans von Berlepsch, Eberhard Riedle, and Jürgen Hauer. "Exciton-Exciton Annihilation as a Mechanism for Uphill Transfer in a Molecular Excitonic System." EPJ Web of Conferences 205 (2019): 06017. http://dx.doi.org/10.1051/epjconf/201920506017.

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Exciton dynamics in a HJ-aggregate of cyanine dye TTBC are investigated by transient absorption with a time resolution of <60 fs and power-dependent emission spectroscopies. Both measurements are consistent with an exciton delocalization length of ~28 monomers. A model assuming diffusive exciton motion reveals that the exciton mobility is at least bimodal and restricted to one spatial dimension. J-band diffusion rates of 2.69 and 2.79e-3 cm2s-1 are found, leading to maximal diffusion lengths of 449 and 14.5 nm. The findings indicate that exciton-exciton annihilation is the origin of effective uphill transfer. This mechanism, if present under solar radiation, maybe useful for organic photovoltaic systems.

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Sotome, Hikaru. "(Invited) Comprehensive Analysis of Exciton Diffusion with Time-Resolved Fluorescence Spectroscopy, Anisotropy and Imaging." ECS Meeting Abstracts MA2024-01, no. 13 (August 9, 2024): 1065. http://dx.doi.org/10.1149/ma2024-01131065mtgabs.

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Excitons produced in materials play a crucial role in photo-energy conversion such as photovoltaics and electroluminescence devices. The temporal and spatial diffusion of excitons is a key factor for dominating the fundamental performance of optoelectronic materials. In this context, analysis of the exciton diffusion dynamics is an important issue for obtaining the rational design of the materials. Excitons diffusing in materials can be characterized by several parameters such as the energy level, orientation of the transition dipole moment and spatial distribution, and the detection of these properties is required for the comprehensive analysis. In the present study, we show time-resolved fluorescence methods for detecting the above relevant properties of excitons. First, time-resolved fluorescence spectroscopy is a basic technique for analyzing the exciton diffusion dynamics. Fluorescence intensity is detected as functions of observation wavelength and time, and the spectral intensity and shift of fluorescence bands provide information on the population of excitons and their energy level. For example, dynamic Stokes shift indicates downhill energy migration and excitons are trapped by the defective site in molecular aggregates. Second, fluorescence anisotropy can be a good indicator for tracking the exciton diffusion in amorphous materials. Fluorescence anisotropy is sensitive to orientation change in transition dipole moments (TDMs) between absorption and fluorescence. In systems where the relative orientation of adjacent molecules is different from each other, such as amorphous solids, the exciton diffusion is accompanied with the change in TDM. Thus, appropriate modeling of molecular alignment enables quantitative estimation of the exciton diffusion coefficient and diffusion length from the anisotropy signal. Finally, time-resolved imaging is a combination of time-resolved spectroscopy and super-resolution microscopy, and an emergent technique for visualizing real-space propagation of excitons in materials. The diffraction-limited excitation beam produces excitons in several hundreds of nanometers and the subsequent exciton diffusion is evaluated by the spatial width of the fluorescence spot. The temporal broadening of the fluorescence spot directly reflects the exciton distribution and we can intuitively obtain the diffusion coefficient and length. Unlike the conventional methods for bulk materials, the advantage of the time-resolved imaging is the applicability to materials with nano- and meso-scale heterogeneous structure and it enables site-selective evaluation of the exciton transport capability. In the conference site, we will also show the application of the above methods to supramolecular polymers and thermally activated delayed fluorescence materials. Figure 1

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Shibu, Abhishek, Camilla Middleton, Carly O. Kwiatkowski, Meesha Kaushal, Jonathan H. Gillen, and Michael G. Walter. "Self-Assembly-Directed Exciton Diffusion in Solution-Processable Metalloporphyrin Thin Films." Molecules 27, no. 1 (December 22, 2021): 35. http://dx.doi.org/10.3390/molecules27010035.

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The study of excited-state energy diffusion has had an important impact in the development and optimization of organic electronics. For instance, optimizing excited-state energy migration in the photoactive layer in an organic solar cell device has been shown to yield efficient solar energy conversion. Despite the crucial role that energy migration plays in molecular electronic device physics, there is still a great deal to be explored to establish how molecular orientation impacts energy diffusion mechanisms. In this work, we have synthesized a new library of solution-processable, Zn (alkoxycarbonyl)phenylporphyrins containing butyl (ZnTCB4PP), hexyl (ZnTCH4PP), 2-ethylhexyl (ZnTCEH4PP), and octyl (ZnTCO4PP) alkoxycarbonyl groups. We establish that, by varying the length of the peripheral alkyl chains on the metalloporphyrin macrocycle, preferential orientation and molecular self-assembly is observed in solution-processed thin films. The resultant arrangement of molecules consequently affects the electronic and photophysical characteristics of the metalloporphyrin thin films. The various molecular arrangements in the porphyrin thin films and their resultant impact were determined using UV-Vis absorption spectroscopy, steady-state and time-resolved fluorescence emission lifetimes, and X-ray diffraction in thin films. The films were doped with C60 quencher molecules and the change in fluorescence was measured to derive a relative quenching efficiency. Using emission decay, relative quenching efficiency, and dopant volume fraction as input, insights on exciton diffusion coefficient and exciton diffusion lengths were obtained from a Monte Carlo simulation. The octyl derivative (ZnTCO4PP) showed the strongest relative fluorescence quenching and, therefore, the highest exciton diffusion coefficient (5.29 × 10−3 cm2 s−1) and longest exciton diffusion length (~81 nm). The octyl derivative also showed the strongest out-of-plane stacking among the metalloporphyrins studied. This work demonstrates how molecular self-assembly can be used to modulate and direct exciton diffusion in solution-processable metalloporphyrin thin films engineered for optoelectronic and photonic applications.

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Luppi, Bruno T., Darren Majak, Manisha Gupta, Eric Rivard, and Karthik Shankar. "Triplet excitons: improving exciton diffusion length for enhanced organic photovoltaics." Journal of Materials Chemistry A 7, no. 6 (2019): 2445–63. http://dx.doi.org/10.1039/c8ta10037c.

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Organic materials containing heavy atoms have been used in photovoltaics to overcome a fundamental limitation: short exciton diffusion length (L_D). We highlight studies showing increased L_D in solar cells using triplet-generating materials and tackle challenges that the field faces with possible avenues for future research.

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Abasto, D. F., M. Mohseni, S. Lloyd, and P. Zanardi. "Exciton diffusion length in complex quantum systems: the effects of disorder and environmental fluctuations on symmetry-enhanced supertransfer." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, no. 1972 (August 13, 2012): 3750–70. http://dx.doi.org/10.1098/rsta.2011.0213.

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Symmetric couplings among aggregates of n chromophores increase the transfer rate of excitons by a factor n 2 , a quantum-mechanical phenomenon called ‘supertransfer’. In this work, we demonstrate how supertransfer effects induced by geometrical symmetries can enhance the exciton diffusion length by a factor n along cylindrically symmetric structures, consisting of arrays of rings of chromophores, and along spiral arrays. We analyse both closed-system dynamics and open quantum dynamics, modelled by combining a random bosonic bath with static disorder. In the closed-system case, we use the symmetries of the system within a short-time approximation to obtain a closed analytical expression for the diffusion length that explicitly reveals the supertransfer contribution. When subject to disorder, we show that supertransfer can enhance excitonic diffusion lengths for small disorders and characterize the crossover from coherent to incoherent motion. Owing to the quasi-one-dimensional nature of the model, disorder ultimately localizes the excitons, diminishing but not destroying the effects of supertransfer. When dephasing effects are included, we study the scaling of diffusion with both time and number of chromophores and observe that the transition from a coherent, ballistic regime to an incoherent, random-walk regime occurs at the same point as the change from supertransfer to classical scaling.

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Guan, Xi, Shiyu Wang, Wenxing Liu, Dashan Qin, and Dayan Ban. "Determining the exciton diffusion length of copper phthalocyanine in operating planar-heterojunction organic solar cells." European Physical Journal Applied Physics 89, no. 3 (March 2020): 30201. http://dx.doi.org/10.1051/epjap/2020190322.

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Organic solar cells based on planar copper phthalocyanine (CuPc)/C60 heterojunction have been characterized, in which a 2 nm-thick layer of bathocuproine (BCP) is inserted into the CuPc layer. The thin layer of BCP allows hole current to tunnel it through but blocks the exciton diffusion, thereby altering the steady-state exciton profile in the CuPc zone (zone 1) sandwiched between BCP and C60. The short-circuit current density (JSC) of device is limited by the hole-exciton scattering effect at the BCP/CuPc (zone 1) interface. Based on the variation of JSC with the width of zone 1, the exciton diffusion length of CuPc is deduced to be 12.5–15 nm. The current research provides an easy and helpful method to determine the exciton diffusion lengths of organic electron donors.

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Nasr, Chouhaid, Toufik Taleb, Roger M. Leblanc, and Surat Hotchandani. "Exciton diffusion length in microcrystalline chlorophyll a." Applied Physics Letters 69, no. 13 (September 23, 1996): 1823–25. http://dx.doi.org/10.1063/1.117445.

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Mikhnenko, Oleksandr V., Hamed Azimi, Markus Scharber, Mauro Morana, Paul W. M. Blom, and Maria Antonietta Loi. "Exciton diffusion length in narrow bandgap polymers." Energy & Environmental Science 5, no. 5 (2012): 6960. http://dx.doi.org/10.1039/c2ee03466b.

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Ortiz, Angy L., Graham S. Collier, Dawn M. Marin, Jennifer A. Kassel, Reynolds J. Ivins, Nicholas G. Grubich, and Michael G. Walter. "The effects of heavy atoms on the exciton diffusion properties in photoactive thin films of tetrakis(4-carbomethoxyphenyl)porphyrins." Journal of Materials Chemistry C 3, no. 6 (2015): 1243–49. http://dx.doi.org/10.1039/c4tc02232g.

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The exciton diffusion coefficient (D) and exciton diffusion length (L_D) for three tetrakis(4-carbomethoxyphenyl)porphyrins were obtained by fitting the quenching efficiency and PL lifetime to a 3D exciton Monte Carlo ediffusion model.

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Gommans, H., S. Schols, A. Kadashchuk, P. Heremans, and S. C. J. Meskers. "Exciton Diffusion Length and Lifetime in Subphthalocyanine Films." Journal of Physical Chemistry C 113, no. 7 (January 26, 2009): 2974–79. http://dx.doi.org/10.1021/jp809802q.

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Dissertations / Theses on the topic "Exciton diffusion length"

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Kholmicheva, Natalia N. "Exciton Diffusion in Nanocrystal Solids." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1498061834549115.

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Wang, Yanbin. "Exciton Harvesting in Ternary Blend Polymer Solar Cells." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/192193.

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Diarra, Cheick Oumar. "Modélisation par dynamique moléculaire ab initio du transport des excitons et du transport thermique dans les semiconducteurs organiques pour la collecte d'énergie." Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAD013.

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L'exciton joue un rôle clé dans le fonctionnement des cellules solaires organiques (OSCs). Comprendre sa dynamique dans les semiconducteurs organiques est essentiel, notamment pour améliorer la longueur de diffusion, une propriété déterminante pour la performance des hétérojonctions planaires, envisagées comme une alternative plus stable aux hétérojonctions en volume (BHJ). Dans la première partie de cette thèse, nous avons développé une approche méthodologique robuste et polyvalente pour évaluer la longueur de diffusion de l'exciton dans les semiconducteurs organiques. Cette approche, basée sur AIMD-ROKS, a été validée avec succès dans le cas du polymère P3HT. Elle a également été appliquée à l'accepteur NFA O-IDTBR, révélant des longueurs de diffusion prometteuses, mais encore insuffisantes pour les hétérojonctions planaires. Dans la deuxième partie de la thèse, le transfert de chaleur dans les semiconducteurs organiques a été exploré, élément crucial pour la performance des dispositifs thermoélectriques. Ces études se sont concentrées sur le P3HT, un matériau utilisé en thermoélectricité. Dans un premier temps, la conductivité thermique au sein des chaînes de P3HT a été étudiée, révélant l'influence de la longueur des chaînes de polymère. Ensuite, les transferts de chaleur entre ces chaînes ont également été examinés
The exciton plays a central role in the functioning of organic solar cells (OSCs). Understanding its dynamics in organic semiconductors is essential, particularly to optimize the diffusion length, a key property for the performance of planar heterojunctions, which are considered as a potentially more stable alternative to bulk heterojunctions (BHJ) in certain contexts. In the first part of this thesis, we developed a robust and versatile methodological approach to evaluate the exciton diffusion length in organic semiconductors. This method, based on AIMD-ROKS, was successfully validated for the P3HT polymer. It was also applied to the NFA O-IDTBR acceptor, revealing promising diffusion lengths, though still insufficient for planar heterojunctions. The second part of the thesis explores heat transfer in organic semiconductors, a crucial element for the performance of thermoelectric devices. These studies focused on P3HT, a material used in thermoelectricity. First, the thermal conductivity within P3HT chains was studied, revealing the influence of polymer chain length. Then, heat transfers between these chains were also examined

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Book chapters on the topic "Exciton diffusion length"

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Jagdishbhai Patel, Mayur, Himangshu Baishya, Ritesh Kant Gupta, Rabindranath Garai, and Parameswar Krishnan Iyer. "Thin Film Solution Processable Perovskite Solar Cell." In Recent Advances in Multifunctional Perovskite Materials. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106056.

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Perovskite has emerged as a promising light-harvesting material for solar cells due to its higher absorption coefficient, bandgap tunability, low-exciton binding energy, and long carrier diffusion length. These lead to high power conversion efficiency >25% for thin film-based perovskite solar cells (PSCs). Additionally, PSCs can be fabricated through simple and cost-effective solution processable techniques, which make this technology more advantageous over the current photovoltaic technologies. Several solution-processable methods have been developed for fabrication of PSCs. In this chapter, the advantages and disadvantages of various solution processable techniques and their scope for large-scale commercialization will be discussed.

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Mbarek, Mohamed, and Kamel Alimi. "Engineering the Color and the Donor-Acceptor Behavior in Nanowires: Blend Versus Coaxial Geometry." In Nanowires - Recent Progress [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94214.

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The blending or the bilayering of two complementary species are the dominant methods for in-solution-processed thin film devices to get a strong donor-acceptor behavior. They propose opposite strategies for the respective arrangement of the two species, a central point for energy and/or charge transfer. In this work, we propose to engineer at the scale of the exciton diffusion length the organization of a donor (poly(vinyl-carbazole), PVK) and an acceptor (poly(para-phenylene-vinylene), PPV) in a nanowire geometry. A two-step template strategy was used to fabricate coaxial nanowires with PPV and PVK, alternatively as the core or the shell material. Their stationary and time-resolved photoluminescence properties were investigated and compared to the case of PVK-PPV blend. Their respective characteristics are direct evidences of the dominant mechanisms responsible for the emission properties.

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Weitz, David A., and David J. Pine. "Diffusing-wave spectroscopy." In Dynamic Light Scattering, 652–720. Oxford University PressOxford, 1993. http://dx.doi.org/10.1093/oso/9780198539421.003.0016.

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Abstract In this chapter we describe a recent development in dynamic light scattering (DLS), which may ultimately have a significant impact on the range of problems that can be addressed and on the types of system that can be studied. We discuss diffusing-wave spectroscopy (DWS), which extends DLS to very highly multiple scattering media. This technique extends the analytic power of DLS to opaque samples such as concentrated suspensions, obviating the need to dilute or index-match. In addition, DWS opens new and exciting possibilities for studying particle dynamics on length scales that are unattainable using conventional methods. We present a summary of the theoretical principles underlying DWS, and discuss its applications, both in extending traditional DLS techniques and in studying new physical phenomena. The development of DWS is still in its relatively early stages, and considerably more work is needed to exploit this technique fully. Our goal here is to provide a comprehensive introduction to the underlying principles, and to provide some examples illustrating the great promise of DWS, in the hope of making further work more productive.

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Conference papers on the topic "Exciton diffusion length"

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Nagamune, Y., H. Watabe, M. Nishioka, and Y. Arakawa. "One-dimensional Exciton Diffusion in GaAs Quantum Wires." In Quantum Optoelectronics. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/qo.1995.qfa5.

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The newly developed micro-photoluminescence measurement at low temperature has revealed one-dimensional diffusion of excitons in GaAs quantum wires with the lateral width of 7 - 30 nm fabricated by the selective growth technique using metal-organic chemical vapor deposition. The observed diffusion length increased with decreasing the wire width from 30 to 15 nm, and decreased from 15 to 7 nm, where the maximum diffusion length was about 4 μm for the 15-nm quantum wire. The change of the diffusion length vs. the wire width is expected to be due to the competition between the one-dimensional character and the interface fluctuation.

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Riley, Drew B., Oskar J. Sandberg, Wei Li, Paul Meredith, and Ardalan Armin. "Quasi-steady-state measurement of exciton diffusion length in organic semiconductors." In Organic Electronics and Photonics: Fundamentals and Devices III, edited by Sebastian Reineke, Koen Vandewal, and Wouter Maes. SPIE, 2022. http://dx.doi.org/10.1117/12.2621270.

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Riley, Drew B., Oskar J. Sandberg, Wei Li, Paul Meredith, and Ardalan Armin. "A quasi steady-state measurement of exciton diffusion length in organic semiconductors." In nanoGe Fall Meeting 2021. València: Fundació Scito, 2021. http://dx.doi.org/10.29363/nanoge.nfm.2021.098.

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Ishii, A., T. Uda, and Y. K. Kato. "Room-temperature single photon emission from micron-long air-suspended carbon nanotubes." In JSAP-OSA Joint Symposia. Washington, D.C.: Optica Publishing Group, 2017. http://dx.doi.org/10.1364/jsap.2017.7p_a404_3.

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Carbon nanotubes have great potential for single photon sources as they have stable exciton states even at room temperature and their emission wavelengths cover the telecommunication bands. In recent years, single photon emission from carbon nanotubes has been achieved by creating localized states of excitons [1]. In contrast to such an approach, here we utilize mobile excitons and show that single photons can be generated at room temperature in air-suspended carbon nanotubes with lengths of several microns. We perform photoluminescence microscopy on as-grown air-suspended carbon nanotubes in order to determine their chirality and suspended length. Photon correlation measurements are performed on nanotube emission at room temperature using a Hanbury-Brown-Twiss setup with InGaAs/InP single photon detectors. We observe antibunching with a clear excitation power dependence, where we obtain g(2)(0) value less than 0.5 at low excitation powers (Fig. 1), indicating single photon generation. We show such g(2)(0) data with different chiralities and suspended lengths, and the effects of long exciton diffusion lengths and efficient exciton-exciton annihilation [2] on single photon generation processes are discussed.

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Betancur, Rafael, Xavier Elias, Saverio Pasini, Luat T. Vuong, Roberto Macovez, and Jordi Martorell. "Novel Organic Solar Cell Design Towards an Optical Control of the Exciton Diffusion Length." In Optics for Solar Energy. Washington, D.C.: OSA, 2010. http://dx.doi.org/10.1364/ose.2010.swd4.

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Jing, Jiang, Emilie Steveler, Nicolas Leclerc, Anthony D'Aléo, Benoit Heinrich, Wilfried Uhring, and Thomas Heiser. "Impact of the crystalline order on the exciton diffusion length in organic thin films of donor-acceptor-donor molecules based on triazatruxene units." In Organic Electronics and Photonics: Fundamentals and Devices III, edited by Sebastian Reineke, Koen Vandewal, and Wouter Maes. SPIE, 2022. http://dx.doi.org/10.1117/12.2615963.

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Riley, Drew B., Oskar J. Sandberg, Wei Li, Paul Meredith, and Ardalan Armin. "Measuring exciton diffusion lengths in organic semiconductors." In nanoGe Spring Meeting 2022. València: Fundació Scito, 2022. http://dx.doi.org/10.29363/nanoge.nsm.2022.295.

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Bueno, Fernando Teixeira, Leonardo Evaristo Souza, Demétrio Antônio da Silva Filho, and Pedro Henrique de Oliveira Neto. "Ab-initio Calculations of Diffusion Lengths and Diffusivities for Singlet Excitons in Organic Materials." In VII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Editora Letra1, 2018. http://dx.doi.org/10.21826/9788563800374049.

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Markillie, G. A. J., J. G. Betterton, H. J. Baker, and D. R. Hall. "High Pressure Operation of a Fast Axial Flow CO2 Laser with a Narrow Gap Slab Radio Frequency Discharge." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cthj2.

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High peak powers, varying pulse lengths and fast repetition frequencies are all desirable features of CO2 laser beams for materials processing applications. Previous device configurations include the TEA laser, generating pulse lengths of ~l-5µs at a pulsed repetition frequency (PRF) to ~400 Hz, and radio frequency (RF) discharge excited diffusion cooled slab waveguide and fast axial flow lasers, which both offer both continuous operation and pulse lengths of 50-100 µs at 5kHz. However, recent developments in materials processing have led to an interest in devices that can deliver shorter pulses than the existing slab or fast flow lasers, but with a much higher PRF than the TEA laser. Fast pulsing of gas lasers requires the switch-off time of the laser to be short compared with the pulse length, a need that is often satisfied by an increase in intracavity pressure. Previous studies of diffusion cooled slab waveguide lasers have shown that operation is possible at high pressures, but that the required cooling of the narrow gap discharge limits efficient operation to pressures of ≤ 300 Torr.

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Zhang, Man. "Large-Eddy Simulation and Linear Acoustic Analysis of a Diffusion Swirling Flame Under Forcing and Self-Excitation." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56405.

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A diffusion swirling flame under external forcing and self-excitation within a single swirler combustor have been studied in this paper with the large-eddy simulation and linear acoustic method. The combustor features pre-vaporized kerosene as the fuel, a single radial air swirler for flame stabilization and a square cross section chamber with adjustable length. Firstly, self-sustained pressure oscillation has been achieved by using of a chocked nozzle on the chamber outlet with large-eddy simulation. Dynamic pressure oscillations are analyzed in frequency domain through Fast Fourier Transform. The major pressure oscillation is identified as the 1st order longitudinal mode of the chamber. Further, the same frequency in the form of harmonic velocity oscillation is imposed on the inlet of the combustor while the chamber length has been changed. Based on this approach, a comparative study of the flame response with different excitation method but same frequency is carried out. In both self-excited and forced cases, global and local flame responses as well as Rayleigh index have been analyzed and compared. With the flame response function, the excited acoustic modes under the influence of dynamic heat release have been predicted with linear acoustic method and compared with the results obtained from large-eddy simulation. Results show that the flame response presents a great difference in the spacial distribution with different excitation approaches. Thermo-acoustic interaction distributes along the flame front with the expansion of the flame under self-excitation while it damps with the acoustic propagating downstream under forcing condition. As the ratio of flame length to acoustic wave length could not be neglected for the diffusion swirling flame, the global flame response under forcing cannot represent the local response feature of the flame accurately, thus influencing the instability prediction.

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