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1
Poulter, Mark W. "Pyroelectric organic thin films." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303623.
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Ma, Fuyuan. "Electrochemically active organic thin films." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0020/NQ44501.pdf.
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Scharnberg, Michael [Verfasser]. "Functional organic thin films / Michael Scharnberg." Kiel : Universitätsbibliothek Kiel, 2008. http://d-nb.info/1019629851/34.
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Greene, Phillip Robert. "Vibrational spectroscopy of thin organic films." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400464.
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Hudson, Andrew James. "Optical applications of ultra-thin organic films." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316871.
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Cooke, Simon J. "Optical devices incorporating ultra-thin organic films." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314837.
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Alexiou, I. "Hole transport materials for organic thin films." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595437.
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The aim of this project is to prepare and characterise novel triarylamine-based hole transport materials for xerographic applications that exhibit favourable electrochemical properties and amorphous nature. As an introduction, the six steps of the xerographic process and the common classes of hole transporting materials are described. The basic theories that have been developed for charge transport are discussed and an overview of the palladium-mediated amination and Suzuki reactions is given. In the following chapters, the synthesis and characterisation of a number of hole transporting triarylamines is reported. A series of linear trimeric arylamines is synthesised using the palladium-catalysed Suzuki protocol and their properties were determined using cyclic voltammetry, thermal gravimetric analysis and differential scanning calorimetry. Similar characterisation is carried out for a number of relatively unsubstituted phenyl and thiophene-based triarylamines. The synthesis of a series of oligomeric materials based on MPPD (Bis-methoxyphenyl-diphenyl-biphenyl-diamine) is reported and their electrochemical and thermal properties are investigated. Thiophene and dioctyl-fluorene-substituted MPPD-derivatives are studied as hole transport materials. Star-shaped and dendritic triarylamines with biphenyl and bithiophene-core molecules are also prepared using palladium-mediated chemistry and characterised. Finally, the attempts to synthesise macrocyclic triarylamine hole transporting materials are described in detail. The charge carrier properties for some of the synthesised materials are measured using the time-of-flight technique of using field-effect-transistors. Each set-up is described in detail and the hole mobility of the materials is calculated. A correlation between structural characteristics and charge-transporting properties is attempted.
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Robinson, Benjamin James. "Molecular Retification from Ultra-Thin Organic Films." Thesis, Bangor University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518694.
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Robaschik, Peter. "Organic semiconductor thin films for spintronic applications." Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/64818.
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Organic semiconductors have a major impact on our daily life, as they are increasingly implemented in commercial devices like organic light emitting diodes (OLED), organic field effect transistors (OFET) or solar cells. Recently, this class of materials became of interest for spintronic applications, which make use of the spin in addition to the charge of the electrons. Due to a high spin life-time and an easy manipulation of the chemical and physical properties, organic molecules become a promising alternative to transition metals and metal oxides for both spin transport and polarisation media. In order to achieve the desired device properties like room temperature operation, it is essential to investigate new materials and fabrication methods. This thesis focuses on vacuum processed organic semiconductor thin films, which further exhibit remarkable magnetic properties, making them suitable for spintronic applications. The materials of choice, iron phthalocyanine (FePc) and manganese phthalocyanine (MnPc), show ferromagnetic behaviour with Curie temperatures of up to 40K and the properties can be tuned by blending with other organic semiconductors. In particular, mixing n-type semiconducting materials such as fluorinated cobalt phthalocyanine (F16CoPc) and tetracyanoquinodimethane (TCNQ) with the p-type magnetic metal phthalocyanines has great potential for both molecular electronics and spintronics. In this work, it was found that the paramagnetic F16CoPc becomes ferromagnetic in a blend with FePc and the coercivity of the compound can be tuned by the concentration. Furthermore, ferromagnetic MnPc films with significant coercivity were obtained by annealing of MnPc:TCNQ blends, which exhibit charge transfer from MnPc to TCNQ in the as-deposited state. Finally, the first spin valves based on FePc were produced and exceptionally large magnetoresistive effects were observed.
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Choi, Jae Hyeok. "Nanomechanical properties of hydrated organic thin films." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42984.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2007.<br>Includes bibliographical references (leaves 167-171).<br>Hydrated organic thin films are biological or synthetic molecularly thin coatings which impart a particular functionality to an underlying substrate and which have discrete water molecules associated with them. Such films exist in biology (e.g. cell membrane lipid bilayers) and have a broad array of potential engineering applications (e.g. biological implant and sensor surfaces, marine antifouling paints etc.). This doctoral thesis focuses on two important classes of hydrated organic thin films that were prepared and studied in vitro. The first model system was an oligo(ethylene oxide)-based self-assembling monolayer (OEO-SAM) which is a synthetic material that is known to exhibit exceptional resistance to nonspecific protein adsorption and, hence, it is a viable candidate for producing implant surfaces with improved biocompatibility. The second model system was the biologically relevant phosphorylcholine(PC)-supported lipid layer which mimics the structure of the cell membrane. The objective of this doctoral thesis was to quantify the functional form of the net surface interaction (force versus separation distance, F(D)), as well as the contact mechanical properties (e.g. elasticity, plasticity, fracture) of these two model systems under different solution conditions, in order to formulate a hypothesis for the molecular origins of the dominant interactions and furthermore, to gain a mechanistic understanding of their in vivo function and performance. For the OEO-SAMs, F(D) was found to exhibit the maximum monotonic repulsive functional form for intermediate surface packing densities (-70%) on loading (approach) and negligible adhesion (Fadhesion<0.3nN) on unloading (retract). Both were attributed to an electrostatic component arising from a dipole induced effective surface charge, as well as a nm-thick hydrated water layer.<br>(cont.) For the PC lipid layers, the effect of length scale on the yield threshold force, Fy, was studied by varying the probe tip end radius, Rtip, used for the surface force measurements. Fy decreased by 20x (Force/Radius) as Rtip increased from 30 nm to 80 nm, presumably due to the fact that the contact area possessed an increased density of molecular-level defects, thereby causing stress concentrations and a reduction in mechanical stability of the layer.<br>by Jae Hyeok Choi.<br>Ph.D.
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Kao, Chi-Yueh. "Thin films of organic-based magnetic semiconductors for organic spintronics." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343748166.
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Beigmohamadi, Maryam. "Growth, structure and morphology of organic thin films." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=985330104.
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Törker, Michael. "Tunneling spectroscopy of highly ordered organic thin films." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2003. http://nbn-resolving.de/urn:nbn:de:swb:14-1056446807640-19877.
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In this work, a Au(100) single crystal was used as substrate for organic molecular beam epitaxy. Highly ordered organic thin films of the molecules 3,4,9,10-perylenetetracarboxylic-3,4,9,10-dianhydrid (PTCDA) and hexa-peri-hexabenzo-coronene (HBC) as well as organic-organic heterostructures on reconstructed Au(100) were prepared. The molecular arrangement was characterized in Scanning Tunneling Microscopy and Low Energy Electron Diffraction investigations. Scanning Tunneling Spectroscopy data were recorded on monolayer and submonolayer PTCDA films. Measurements on closed PTCDA layers at different fixed tip sample separations revealed a peak +0.95V. Other measurements performed consecutively on a PTCDA island and on uncovered Au(100) areas showed that this peak is indeed caused by the PTCDA molecules. Another set of consecutive measurements on herringbone and square phase PTCDA islands indicates that in the normalized differential conductivity the peak shape and peak position depend on the molecular arrangement. The STS data are compared to UPS and IPES results, already published. In the case of highly ordered films of HBC on Au(100) it was possible to derive the energetic positions of the HBC frontier orbitals and the energies of the molecular states next to these frontier orbitals from Tunneling Spectroscopy measurements. These measurements were performed using two different tip materials. The results are compared to UPS measurements, to theoretical calculations of the electronic conductance based on a combination of the Landauer transport formalism with a density-functional-parametrized tight-binding scheme within the Local Density Approximation (LDA) as well as semiempirical quantum chemistry calculations<br>Für die hier dargestelleten Arbeiten wurde ein Au(100) Einkristall als Substrat für die organische Molekularstrahlepitaxie verwendet. Hochgeordnete organische Dünnschichten der Moleküle 3,4,9,10-Perylen-tetracarbonsäure-3,4,9,10-dianhydrid (PTCDA) und Hexa-peri-hexabenzo-coronen (HBC) sowie organisch-organische Heteroschichten wurden auf der Au(100) Oberfläche abgeschieden. Die Struktur der Schichten wurde mittels Rastertunnelmikroskopie (STM) und Niederenergetischer Elektronenbeugung (LEED) untersucht. Tunnelspektroskopiedaten wurden für Monolagen sowie Submonolagen von PTCDA aufgenommen. Messungen an geschlossenen PTCDA Filmen zeigen für verschiedene Probe-Spitze-Abstände ein Maximum in der normierten differentiellen Leitfähigkeit bei +0.95V. Aufeinanderfolgende Messungen auf PTCDA-Inseln und unbedeckten Gebieten der Au(100) Oberfläche zeigen eindeutig, dass dieses Maximum auf die PTCDA Moleküle zurückzuführen ist. Weitere Messungen an PTCDA Inseln unterschiedlicher Struktur (Fischgrätenstruktur bzw. quadratische Struktur) belegen einen Zusammenhang zwischen der Anordnung der Moleküle und der Peakposition bzw. Peakform in der normierten differentiellen Leitfähigkeit. Die STS Daten werden mit UPS und IPES Ergebnissen aus der Literatur verglichen. Im Falle hochgeordneter HBC Schichten auf Au(100) war es möglich, neben dem höchsten besetzten und niedrigsten unbesetzten Molekülorbital auch die energetische Position der jeweils nächsten Orbitale zu bestimmen. Diese Messungen wurden mit zwei unterschiedlichen Spitzenmaterialien durchgeführt. Die Ergebnisse für HBC auf Au(100) werden mit UPS Daten sowie mit theoretischen Rechnungen verglichen
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Törker, Michael. "Tunneling spectroscopy of highly ordered organic thin films." Doctoral thesis, Technische Universität Dresden, 2002. https://tud.qucosa.de/id/qucosa%3A24233.
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In this work, a Au(100) single crystal was used as substrate for organic molecular beam epitaxy. Highly ordered organic thin films of the molecules 3,4,9,10-perylenetetracarboxylic-3,4,9,10-dianhydrid (PTCDA) and hexa-peri-hexabenzo-coronene (HBC) as well as organic-organic heterostructures on reconstructed Au(100) were prepared. The molecular arrangement was characterized in Scanning Tunneling Microscopy and Low Energy Electron Diffraction investigations. Scanning Tunneling Spectroscopy data were recorded on monolayer and submonolayer PTCDA films. Measurements on closed PTCDA layers at different fixed tip sample separations revealed a peak +0.95V. Other measurements performed consecutively on a PTCDA island and on uncovered Au(100) areas showed that this peak is indeed caused by the PTCDA molecules. Another set of consecutive measurements on herringbone and square phase PTCDA islands indicates that in the normalized differential conductivity the peak shape and peak position depend on the molecular arrangement. The STS data are compared to UPS and IPES results, already published. In the case of highly ordered films of HBC on Au(100) it was possible to derive the energetic positions of the HBC frontier orbitals and the energies of the molecular states next to these frontier orbitals from Tunneling Spectroscopy measurements. These measurements were performed using two different tip materials. The results are compared to UPS measurements, to theoretical calculations of the electronic conductance based on a combination of the Landauer transport formalism with a density-functional-parametrized tight-binding scheme within the Local Density Approximation (LDA) as well as semiempirical quantum chemistry calculations.<br>Für die hier dargestelleten Arbeiten wurde ein Au(100) Einkristall als Substrat für die organische Molekularstrahlepitaxie verwendet. Hochgeordnete organische Dünnschichten der Moleküle 3,4,9,10-Perylen-tetracarbonsäure-3,4,9,10-dianhydrid (PTCDA) und Hexa-peri-hexabenzo-coronen (HBC) sowie organisch-organische Heteroschichten wurden auf der Au(100) Oberfläche abgeschieden. Die Struktur der Schichten wurde mittels Rastertunnelmikroskopie (STM) und Niederenergetischer Elektronenbeugung (LEED) untersucht. Tunnelspektroskopiedaten wurden für Monolagen sowie Submonolagen von PTCDA aufgenommen. Messungen an geschlossenen PTCDA Filmen zeigen für verschiedene Probe-Spitze-Abstände ein Maximum in der normierten differentiellen Leitfähigkeit bei +0.95V. Aufeinanderfolgende Messungen auf PTCDA-Inseln und unbedeckten Gebieten der Au(100) Oberfläche zeigen eindeutig, dass dieses Maximum auf die PTCDA Moleküle zurückzuführen ist. Weitere Messungen an PTCDA Inseln unterschiedlicher Struktur (Fischgrätenstruktur bzw. quadratische Struktur) belegen einen Zusammenhang zwischen der Anordnung der Moleküle und der Peakposition bzw. Peakform in der normierten differentiellen Leitfähigkeit. Die STS Daten werden mit UPS und IPES Ergebnissen aus der Literatur verglichen. Im Falle hochgeordneter HBC Schichten auf Au(100) war es möglich, neben dem höchsten besetzten und niedrigsten unbesetzten Molekülorbital auch die energetische Position der jeweils nächsten Orbitale zu bestimmen. Diese Messungen wurden mit zwei unterschiedlichen Spitzenmaterialien durchgeführt. Die Ergebnisse für HBC auf Au(100) werden mit UPS Daten sowie mit theoretischen Rechnungen verglichen.
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Hodges, Ping Y. "Electro-optical Properties of Ultra-Thin Organic Films." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32070.
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Electro-optical properties of thin film are of great interest owing to the perpetual demand for miniaturization and higher speed devices for communication, electronic, and biomedical applications. The thickness of polymer films developed for these applications has decreased dramatically making interfacial effects significant. It is well documented that, in submicron thickness range, both film/substrate & film/air interface are critical. In this study, we probe the dynamics of electro-optical polymer thin films in the sub-micron thickness regime to understand interfacial effects. The polymer chain dynamics of Polypropylene oxide (PPO) under electric field are investigated in this study. The effects of electric field strength, frequency, and polymer molecular weight on the polymer chain dynamics under electric field are studied. Experimental results show that PPO exhibits both piezoelectric and electrorestrictive effects at significantly high frequencies (101kHz range). Conventional organic materials are responsive only at frequencies in <1kHz range. A high signal-to-noise ratio differential interferometry is designed to quantitatively study the effects of film thickness, electric field frequency and amplitude on the dynamic properties of PPO thin films ranging from 30 nm to 400 nm. The interferometer can concurrently monitor the index of refraction, thickness change of polymer films, and birefringence due to the applied electrical field.<br>Master of Science
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Bommel, Sebastian. "Unravelling nanoscale molecular processes in organic thin films." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17315.
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Dünne Filme aus konjugierten Molekülen werden vermehrt in der organischen Optoelektronik, Bio-Sensorik und Oberflächenmodifikationen eingesetzt. Jedoch steckt das nanoskopische Verständnis von elementaren Prozessen bzgl. des molekularen Wachstums, der Film-Stabilität und thermisch-mechanischer Eigenschaften noch in den Kinderschuhen. Im ersten Teil dieser Arbeit nutzen wir Echtzeit in situ spekulare und diffuse Röntgenstreuung in Kombination mit Kinetik-Monte-Carlo Simulationen, um die Nukleation und das Multilagen-Wachstum von C60 zu studieren. Wir quantifizieren einen konsistenten Satz von Energieparametern, die die Oberflächenprozesse während des Wachstums beschreiben: eine effektive Ehrlich-Schwoebel Barriere von EES = 110 meV, eine Oberflächendiffusions-Barriere von ED = 540 meV und die Bindungsenergie von EB = 130 meV. Durch die Analyse der Teilchendynamiken finden wir, dass die laterale Diffusion ähnlich derer von Kolloiden ist, jedoch weist die Stufenkanten-Diffusion eine atom-ähnlichen Schwoebel-Barriere auf. Außerdem haben wir für die erste Monolage ein thermisch-aktiviertes Dewetting nach dem Wachstum von C60 auf Mica mit einer effektiven Aktivierungsbarriere von (0.33 ± 0.14) eV für die Aufwärts-Diffusion beobachtet. Im zweiten Teil der Arbeit untersuchen wir die thermomechanischen Eigenschaften der supra-molekularen Anordnung von dem organischen Halbleiter PTCDI-C8. Temperaturabhängige GIXD-Experimente decken einen außergewöhnlich großen positiven und negativen thermischen Expansionskoeffizienten der Kristallstruktur auf. Die Moleküle vollführen kooperative rotierende Bewegungen als Reaktion auf die Temperaturänderung, die zu dieser anomalen thermischen Expansion führen. Unsere Beschreibung der Bewegungen einzelner adsorbierter Moleküle während des Wachstums und der kooperativen Bewegungen einzelner Moleküle in supra-molekularen Ensembles auf der molekularen Skala wird die weitere Arbeit auf dem Weg zu funktionalen molekularen dünnen Filmen beleben.<br>Thin films of conjugated molecules are increasingly used in organic optoelectronics, biosensing and surface modification. However, nanoscopic understanding of elementary processes regarding the molecular film growth, the stability of these films and regarding the thermal and mechanical properties of supra-molecular assemblies are in its infancy. In the first part of this thesis we use real-time in situ specular and diffuse X-ray scattering in combination with kinetic Monte Carlo simulations to study C60 nucleation and multilayer growth. We quantify a consistent set of energy parameters, which describe the surface processes during growth, yielding an effective Ehrlich-Schwoebel barrier of EES = 110 meV, a surface diffusion barrier of ED = 540 meV and a binding energy of EB = 130 meV. Analysing the particle-resolved dynamics, we find that the lateral diffusion is similar to colloids, but step-edge crossing is characterized by an atom-like Schwoebel barrier. Furthermore, a thermally-activated post-growth dewetting for C60 on mica has been observed for the first monolayer with an effective activation barrier for upward interlayer transport of (0.33 ± 0.14) eV. In the second part we investigate the thermomechanical properties of the supra-molecular assembly of the organic semiconductor PTCDI-C8. Temperature-dependent Grazing Incidence X-ray Diffraction (GIXD) experiments reveal extraordinary large positive and, surprisingly, negative thermal expansion coefficients of the thin film crystal structure. The molecules perform temperature-controlled cooperative rotational motions leading to the change of the molecular crystal structure at different temperatures. We hope that our molecular scale picture of the movement of single ad-molecules during growth and the cooperative motions of single molecules in supra-molecular ensembles will stimulate further work towards the optimized, rational design of functional molecular thin films and nanomaterials.
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Zheng, Ying. "Nanostructured thin films for organic photovoltaic cells and organic light-emitting diodes." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024921.
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Allen, R. A. "Structure and properties of azobenzene thin films." Thesis, Lancaster University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379750.
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Ekstrand, Paul Daniel. "Magnetic relaxation in iron phthalocyanine thin films." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1604875.
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<p> Magnetic relaxation describes the process by which a magnetic system prepared in a non-equilibrium state returns to an equilibrium distribution. Thin film samples of iron phthalocyanine (FePc) are deposited onto heated substrates. Substrates are made of either silicon, or smooth gold on silicon. FePc molecules self-assemble into small crystalline structures. Due to the planar shape of the molecules, iron chains are formed. The length of these chains depends on the deposition temperature of the sample. Here, FePc thin films are saturated in an applied magnetic field of 3 T at low temperatures. The magnetic field is then reduced to 0 T at a rate of either 54 Oe/s or 100 Oe/s. The change of the magnetization at zero-field and constant temperature is recorded over a time interval of 5000 s. A series of 200 nm thick FePc samples are prepared at varying deposition temperatures onto silicon substrates. Based on the separation distance between iron chains, the inter-chain interactions—probably based on dipole interactions—is expected to be small. The intra-chain interactions are modified by the grain size. Using the stretched exponential model, a non-vanishing asymptotic remnant magnetization is found. The value of this asymptote is shown to decay exponentially with measurement temperature, and vanish near 4.5 K. The dynamic response has a peak which becomes higher in temperature with larger grain size up to 180°C, where we expect a phase transition in the thin film morphology. Above 3.2 K, the relaxation time appears activated, but the data is inconclusive at this moment. From these results, we find that both static and dynamic magnetic responses play an important role in FePc thin films in the measured temperature range of 2.5 K to 4.0 K. Asymptotic remnant magnetization, the static variable, is only non-zero below 4 K and importantly depends on the grain size as larger grains tend to make the inter-chain interactions more important.</p>
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Sykesud, Christopher Geoffrey Dominic. "New organic materials for gas sensing by optical means." Thesis, Coventry University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282602.
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Agbor, N. E. "Gas sensors using organic thin films at room temperature." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5694/.
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The thesis describes work on the thin film deposition, characterization and gas sensing of three groups of organic materials: polyaniline, lutetium bisphthalocyanine and metallotetraphenylporphyrins. These materials were deposited by evaporation, spinning and using the Langmmr-Blodgetttechnique. Film characterization by dc conductivity, scanning electronmicroscopy, surface plasmon resonance, ultraviolet/visible and infrared spectroscopy is described. Gas-induced changes in devices coated with the thinorganic films were monitored at the molecxilar level using Fourier transform infrared spectroscopy and at the macroscopic level using a chemiresistor and surface plasmon resonance. The gases used have included NO(_x), H(_2)S, SO(_2), COand CH(_4) at room temperature and pressure. Devices made with the thinorganic films were reversibly sensitive to some of the gases at low concentrations (<10ppm), but the reactions were irreversible at high concentrations (>100ppm). Polyaniline is shown to exhibit a different chemical structure, reflecting the conditions of its deposition. Spun films were found to be in the emeraldine baseform, the evaporated films were physically and chemically similar toleucoemeraldine base while the Langmuir-Blodgett films were closer topemigraniline, the completely oxidized form of polyaniline. All the types of polyaniline films were sensitive to H(_2)S and NO(_x) concentrations down to4ppm. Only spun and evaporated films were responsive to SO(_2). The spun layers were most sensitive to SO2 and least sensitive to NO(_x)- In contrast, the evaporated layers were most sensitive to NO(_x)- The changes recorded in these measurements occurred after a delay time of few seconds, but were complete lyirreversible for exposure to high gas concentrations. However, no response was observed when exposed to CO or CH(_4) even at very high concentrations. Infrared spectroscopy studies indicated the irreversible changes, for example when exposed to NO(_x), are due oxidation of benzoid rings into quinoid structures. Lutetium bisphthalocyanine has been deposited by the Langmuir-Blodgett technique. Using changes in conductivity, LB layers of lutetium bisphthalocyanine showed responses to NO(_x), H(_2)S and SO(_2) at concentrations below l00ppm. However, using surface plasmon resonance, only the NO(_x), induced changes could be measured at concentrations below l00ppm. These responses- occurred after a delay time of a few seconds and were partially reversible. Cobalt (II) methoxyltetraphenyl porphyrin has been deposited mainly by the Langmuir-Blodgett technique. Gas induced changes in the film were monitored using changes in dc conductivity and surface plasmon resonance. In all cases, NO(_x) was reversibly detected, but at a much higher concentration (>100ppm)than for the other materials in this thesis.
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Foster, Kathryn Ellen. "Thin aligned organic polymer films for liquid crystal devices." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4895/.
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This project was designed to investigate the possibility of producing alignment layers for liquid crystal devices by cross-linking thin films containing anisotropic polymer bound chromophores via irradiation with polarised ultra violet light. Photocross-linkable polymers find use in microelectronics, liquid crystal displays, printing and UV curable lacquers and inks; so there is an increasing incentive for the development of new varieties of photopolymers in general. The synthesis and characterisation of two new photopolymers that are suitable as potential alignment layers for liquid crystal devices are reported in this thesis. The first polymer contains the anthracene chromophore attached via a spacer unit to a methacrylate backbone and the second used a similarly attached aryl azide group. Copolymers of the new monomers with methyl methacrylate were investigated to establish reactivity ratios in order to understand composition drift during polymerisation.
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Adianto. "Plasma polymerized organic thin films applied to electronic devices." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386600.
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Madigan, Conor (Conor Francis) 1978. "Aspects of exciton behavior in amorphous organic thin films." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87250.
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Yuan, Quan. "The microstructures of organic thin films for transistor applications /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Banimuslem, Hikmat Adnan. "Organic/carbon nanotubes hybrid thin films for chemical detection." Thesis, Sheffield Hallam University, 2015. http://shura.shu.ac.uk/19312/.
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Metallophthalocyanines (MPcs) are classified as an important class of conjugated materials and they possess several advantages attributed to their unique chemical structure. Carbon nanotubes (CNT), on the other hand, are known to enhance the properties of nano-composites in the conjugated molecules, due to their one dimensional electronic skeleton, high surface area and high aspect ratio. In this thesis, work has been carried out on the investigation of different substituted metal-phthalocyanines with the aim of developing novel hybrid film structures which incorporates these phthalocyanines and single-walled carbon nanotubes (SWCNT) for chemical detection applications. Octa-substituted copper phthalocyanines (CuPcR[8]) have been characterised using UV-visible absorption spectroscopy. Obtained spectra have yielded an evidence of a thermally induced molecular reorganization in the films. Influence of the nature of substituents in the phthalocyanine molecule on the thin films conductivity was also investigated. Octa-substituted lead (II) phthalocyanines (PbPcR[8]) have also been characterized using UV-visible spectroscopy. Sandwich structures of ITO/PbPcR[8]/In were prepared to investigate the electronic conduction in PbPcR[8]. The variation in the J(V) behavior of the films as a result of heat treatment is expected to be caused by changes in the alignment inside the columnar stacking of the molecules of the films. Thin films of non-covalently hybridised SWCNT and tetra-substituted copper phthalocyanine (CuPcR[4]) molecules have been produced. FTIR, DC conductivity, SEM and AFM results have revealed the [mathematical equation]; interaction between SWCNTs and CuPCR[4] molecules and shown that films obtained from the acid-treated SWCNTs/CuPcR[4] hybrids demonstrated more homogenous surface. Thin films of pristine CuPCR[4] and CuPcR[4]/S WCNT were prepared by spin coating onto gold-coated glass slides and applied as active layers for the detection of benzo[a]pyrene, pentachlorophenol (PCP), 2-chlorophenol, diuron and simazine in water as well as amines vapours in ambient air utilizing total internal reflection spectroscopic ellipsometry (TIRE) as an optical detection method. Different concentrations of pesticides in water ranging from 1 to 25 mug/L have been examined. It was revealed that the shifts in [mathematical equation] spectra of CuPcR[4]SWCNT films were evidently larger than those produced by the pristine CuPcR[4] films, indicating largely improved films' sensitivity of the hybrid films. Adsorption of amines onto films' surfaces has been realised by monitoring changes in the phase shift [mathematical equation] of TIRE. Methylamine has shown higher sensitivity and lower response time among the studied amines. For all amines vapours, the sensitivity of SWCNT/CuPcR[4] hybrid films was higher than the sensitivity of pristine Cu[1]PCR[4] films. Further work has been carried out on hybrids of SWCNT with zinc phthalocyanines (ZnPc). Thin films of pristine SWCNT and SWCNT/ZnPc hybrids were prepared by drop casting onto interdigitated electrodes and applied as active layers to detect ammonia vapor by measuring electrical resistance changes. Influence of pyrene substituent in the phthalocyanine ring on the hybrid formation and their sensor response has also been verified.
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Scidà, Alessandra <1985>. "Ion implantation of organic thin films and electronic devices." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5205/1/Scid%C3%A0_Alessandra_Tesi.pdf.
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Organic semiconductors have great promise in the field of electronics due to their low cost in term of fabrication on large areas and their versatility to new devices, for these reasons they are becoming a great chance in the actual technologic scenery. Some of the most important open issues related to these materials are the effects of surfaces and interfaces between semiconductor and metals, the changes caused by different deposition methods and temperature, the difficulty related to the charge transport modeling and finally a fast aging with time, bias, air and light, that can change the properties very easily. In order to find out some important features of organic semiconductors I fabricated Organic Field Effect Transistors (OFETs), using them as characterization tools.
The focus of my research is to investigate the effects of ion implantation on organic semiconductors and on OFETs. Ion implantation is a technique widely used on inorganic semiconductors to modify their electrical properties through the controlled introduction of foreign atomic species in the semiconductor matrix. I pointed my attention on three major novel and interesting effects, that I observed for the first time following ion implantation of OFETs:
1) modification of the electrical conductivity;
2) introduction of stable charged species, electrically active with organic thin films;
3) stabilization of transport parameters (mobility and threshold voltage).
I examined 3 different semiconductors: Pentacene, a small molecule constituted by 5 aromatic rings, Pentacene-TIPS, a more complex by-product of the first one, and finally an organic material called Pedot PSS, that belongs to the branch of the conductive polymers. My research started with the analysis of ion implantation of Pentacene films and Pentacene OFETs. Then, I studied totally inkjet printed OFETs made of Pentacene-TIPS or PEDOT-PSS, and the research will continue with the ion implantation on these promising organic devices.
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Scidà, Alessandra <1985>. "Ion implantation of organic thin films and electronic devices." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5205/.
Full textAbstract:
Organic semiconductors have great promise in the field of electronics due to their low cost in term of fabrication on large areas and their versatility to new devices, for these reasons they are becoming a great chance in the actual technologic scenery. Some of the most important open issues related to these materials are the effects of surfaces and interfaces between semiconductor and metals, the changes caused by different deposition methods and temperature, the difficulty related to the charge transport modeling and finally a fast aging with time, bias, air and light, that can change the properties very easily. In order to find out some important features of organic semiconductors I fabricated Organic Field Effect Transistors (OFETs), using them as characterization tools.
The focus of my research is to investigate the effects of ion implantation on organic semiconductors and on OFETs. Ion implantation is a technique widely used on inorganic semiconductors to modify their electrical properties through the controlled introduction of foreign atomic species in the semiconductor matrix. I pointed my attention on three major novel and interesting effects, that I observed for the first time following ion implantation of OFETs:
1) modification of the electrical conductivity;
2) introduction of stable charged species, electrically active with organic thin films;
3) stabilization of transport parameters (mobility and threshold voltage).
I examined 3 different semiconductors: Pentacene, a small molecule constituted by 5 aromatic rings, Pentacene-TIPS, a more complex by-product of the first one, and finally an organic material called Pedot PSS, that belongs to the branch of the conductive polymers. My research started with the analysis of ion implantation of Pentacene films and Pentacene OFETs. Then, I studied totally inkjet printed OFETs made of Pentacene-TIPS or PEDOT-PSS, and the research will continue with the ion implantation on these promising organic devices.
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Hao, Shuang. "Josephson tunnel junctions using Langmuir-Blodgett films." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252717.
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Lau, Kwok Hing Connie. "Stacked organic light emitting diode." HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/916.
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Omar, Ozma. "Optical effects in Langmuir-Blodgett films of novel organic materials." Thesis, Sheffield Hallam University, 1998. http://shura.shu.ac.uk/20143/.
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The high level of molecular control makes the Langmuir-Blodgett (LB) technique an appealing method of film deposition. The uniform nature of the films produced allows convenient investigation of intermolecular interactions and provides information pertaining to the orientation of molecules within films. LB films of two amphiphilic materials with contrasting molecular structures have been deposited. AmPc5 (a metal-free phthalocyanine (pc)) is a two-dimensional, cyclic molecule, whereas AmAzl (a resorcinol calixarene) possesses a three-dimensional basket-type structure. The amphiphilic nature of both molecules is as a result of functional side-chains. The AmPc5 spreading solution was prepared by dissolving in trichloroethane to a concentration of 0.1 mg/ml. After spreading 500-600 ul, the resulting Langmuir film was found to have a critical pressure of 28 mN/m and an area per molecule of 1.61 nm2 on the water surface. Monolayer deposition onto glass substrates enabled spectroscopic examination of the films and comparison to solution spectra. The solution spectrum shows the split Q-band absorption peaks at 700 nm and 733 nm characteristic of metal-free pc's. The LB film spectrum shows a broadening of both peaks and a red shift of the 733 nm peak, and a blue shift of the 700 nm peak. The 700 nm peak is suppressed as a result of the stack-like packing structure of AmPc5. Absorption spectra of floating AmPc5 monolayers imply that the material does not assume the monomer state at any stage of compression. This is characteristic of rigid molecules that induce order within the floating monolayer. The refractive indices (n) and extinction coefficients (k) were determined across the visible wavelength range. Both the n and k values are shown to increase with monolayer thickness, although the n value tends towards a steady value of 2.1. Deposition onto gold coated glass substrates enabled surface plasmon resonance analysis and determination of n and k at specific film thickness'. The n was found to increase with film thickness, tending towards a steady state value of 2.0. This is in excellent agreement with spectroscopic analysis. Absorption spectra measured using polarised light show AmPc5 exhibits dichroism. The calculations indicate that the pc ring lies almost perpendicular to the substrate. AmAzl was dissolved in chloroform to a concentration of 0.5 mg/ml with 10% ethanol to aid solubility. The optimum solution spreading quantity required to form a floating monolayer was found to be between 50 and 100 ul. The film was shown to have a critical pressure of 30 mN/m and an area per molecule of 1.86 nm2 on the water surface. Both LB film and solution spectra show a single absorbance peak at 454 nm which is due to transitions in the azo functional side chains. Calculation of n and k shows that they tend towards steady values of 1.5 and 2.0, respectively. The n obtained via surface plasmon resonance analysis shows a steady state value of 1.43 on silver coated glass and 1.35 on gold coated glass. This suggests a different type of packing structure on all three substrates. The lack of dichroism exhibited by AmAzl indicates the formation of in-plane amorphous films. AmAzl was deposited in alternating layers with tricosenoic acid. The structure was confirmed by X-ray diffraction studies and investigated using second harmonic generation. The second harmonic signal was shown to be proportional to the square of the number of bilayers.
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Effertz, Christian [Verfasser]. "Organic molecular crystals: from thin-films to devices : investigation of thin-film formation and electronic transport properties of polycrystalline perylene films / Christian Effertz." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1018191550/34.
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Dalkiranis, Pereira Gustavo Gonçalves. "Thermal transport and thermoelectricity in organic and inorganic thin films." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667873.
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Yang, Dengliang. "Charge transport and chemical sensing properties of organic thin-films." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3262181.
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Thesis (Ph. D.)--University of California, San Diego, 2007.<br>Title from first page of PDF file (viewed July 10, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 104-113).
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Ferguson, Andrew John. "Photophysical properties of organic thin films grown by vapour deposition." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420394.
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Eyre, Graham Robert. "Deposition of organic thin films by plasma and photochemical techniques." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/9319/.
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The work detailed in this thesis concerns organic thin films synthesised either using R.F. inductively coupled plasmas excited in unsaturated monomers containing either fluorine or a nitrile group, or else irradiating the said monomers in vacuo using ultraviolet light. The effect of the following parameters on the composition and structure of the resultant films was determined using ESCA/XPS : a) power input to the R.F. plasma system, b) photon flux during UV irradiation, c) monomer type (including structural isomerism), and d) monomer flow rate. Relative system deposition rates were rationalised in terms of Yasuda's parameter, W/FM, which was found to hold true qualitatively, if not quantitatively. Introduction of halogen vapour to the plasma system in the presence of nitrile monomers physically decreased the glow volume. Analysis by ESCA and UV absorption spectroscopy revealed the presence of ionic halogen species in the resultant films. An overall decrease in deposition rate of the system was also observed. A similar result for the latter was seen for UV irradiation in the presence of iodine. The results were rationalised by assigning a free radical mechanism for both plasma and photochemical film deposition which is inhibited by halogens. Films formed by irradiation at >200 nm were found to have differing chemical compositions compared to those obtained in the vacuum ultraviolet (<200 nm). This result was attributed to the differing photochemistries occurring in the two wavelength regions. Reference to the gas-phase photochemical literature enabled identification of the likely intermediates and term states involved, including 1,1 and 1,2 molecular elimination from ethylenic monomers in the vacuum UV to give the respective ethynes, together with secondary photolysis products. Consequently a mechanism for surface photopolymerisation was outlined which was compared with that proposed for plasma polymerisation, both of which involve vibrationally excited ground states for the monomers studied.
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Mei, Jun S. B. Massachusetts Institute of Technology. "Photoluminescence quenching of organic thin films by transparent conductive oxides." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35059.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.<br>Includes bibliographical references (p. 83-86).<br>One fundamental challenge in designing organic light-emitting diodes is luminescence quenching near an electrode. In this work, we investigate the underlying mechanism behind luminescence quenching by measuring the reduction in Alq3 photoluminescence due to SnO02. Using an analytical model and a Monte Carlo simulation for exciton dynamics in amorphous organic solids, we find that the exciton diffusion length in bulk Alq3 is in the range of 70--80 A. We also find that for SnO2 films deposited without oxygen in the sputtering ambient, resonant energy transfer from Alq3 to SnO2 is the dominant quenching mechanism. By varying the oxygen content in the Ar/C)2 sputtering gas mixture, we find that the energy transfer distance decreases from 10--25 A for 0% 02 to less than 2 A for 10% 02. Our experimental results suggest that because excess oxygen reduces oxygen vacancies and defect electronic states in SnO2, it leads to a smaller spectral overlap between the emission of Alq3 and the absorption of SnO2, thereby shortening the energy transfer distance and reducing the quenching capability of SnO2.<br>by Jun Mei.<br>S.B.
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Gaskins, Kylie. "Organic Self-Assembled Thin Films for Second Order Nonlinear Optics." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/34261.
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With a growing demand in industry for cost effective, increased data handling capabilities great attention has been paid to the study of various polymer systems for use in optical telecommunications. Inorganic crystals, currently used in such systems, have high performance, but are more expensive and less obtainable than organic materials. Recent advances in techniques for developing highly efficient and inexpensive organic polymeric electro-optic (EO) devices compatible with current state-of-the-art electronics have created an interest in the commercialization of such electro-optic devices. In light of the many advantages of utilizing organic materials for electro-optic applications, numerous methods have been developed to produce nonlinear optically (NLO)-active polymeric films for such purposes. Ionic self-assembled multilayer (ISAM) films are a recently developed class of materials that allows detailed structural and thickness control at the molecular level, combined with ease of manufacturing and low cost. However, the layer-by-layer deposition technique utilized for this method currently requires lengthy processing times that challenge the feasibility of fabricating a thick film suitable for EO modulator device fabrication.
This study focuses on addressing the influence of several pertinent processing variables affecting these challenges for application to electro-optic device fabrication. This study investigated (1) the effect of forced convection, varying deposition time and varying dye concentration on the properties of PAH/Procion Brown films fabricated via the hybrid reactive deposition scheme, (2) the automation and optimization of the fabrication of thick NLO active films and (3) the use of the hybrid covalent-electrostatic deposition scheme to fabricate a polymeric waveguide device with an electro-optic coefficient comparable to that of lithium niobate (LiNbO3).
At fixed deposition time and concentration conditions, the presence of convection had little demonstrated effect on films with deposition times shorter than 2 minutes. For the 5 minute case, the presence of convection correlated with a ~45% increase in Ï (2)zzz values values and a 25% increase in absorbance per bilayer. At a constant dye concentration of 5 mg/ml, the deposition time had little effect on SHG for deposition times less than two minutes. In the presence of convection, the increase in deposition time from 2 minutes to 5 minutes showed a 57% increase in Ï (2)zzz values and a 30% increase in absorbance per bilayer. For a deposition time of 2 minutes in the presence of convection, the dye solution concentration was successfully reduced 5-fold (from 5 mg/ml to 1 mg/ml) with less than a 5% difference in Ï (2)zzz values, less than a 15% decrease in absorbance per bilayer and no detriment to film quality. These results strongly indicate that the deposition conditions remain well outside of the transport-limited regime at a dye concentration of 1 mg/ml. Rather, the surface reaction rate apparently is controlling. Depositing slides at an elevated temperature (~35°C), had an undetermined effect on Ï (2)zzz values, but showed a 15% increase in absorbance per bilayer.
An automatic dipper was programmed to replicate the current manual deposition method to fabricate a film suitable for EO modulator devices. Utilizing the optimal conditions for the processing variables, an optically-homogeneous, 100 nm-thick film was fabricated utilizing the automated process, yielding a Ï (2)zzz values~ 23 x 10-9 esu.
A three-layer coplanar electro-optic device was fabricated utilizing the hybrid reactive deposition method. For this device, the presence of added salt was found to increase the electro-optic coefficient r33 by a factor of 3 compared to its value when made with no added salt. The electro-optic coefficient of the added salt case was found to be about 1/2 that of lithium niobate (LiNbO3).<br>Master of Science
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Benedetto, Alessandro. "Grafting organic thin films for the lubrification of electrical contacts." Paris 11, 2008. http://www.theses.fr/2008PA112352.
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Au cours de cette thèse a été étudié le rôle de films minces organiques immobilisés comme lubrifiants pour les contacts électriques. Les films minces ont été électrogreffés sur or qui est un métal couramment utilisé comme revêtement métallique final de certains connecteurs électriques bas-niveau. Les films étudiés appartiennent à deux familles : les poly(methacrylate)s obtenus par électrogreffage cathodique et des films de type poly(phenylene) obtenus par la réduction électrochimique de sels de diazonium aromatiques. Des films composites de poly(methacrylate) électrogreffés avec des nanotubes de carbone ou des polymères conducteurs ont été aussi réalisés. D’abord le comportement électrochimique des molécules de départ puis le greffage électrochimique des films ainsi que leur propriétés physico-chimiques ont été étudiés. Ensuite des tests tribologiques et électriques ont été effectués sur les substrats fonctionnalisés pour étudier l’effet lubrifiant des films organiques et la résistance électrique du contact ainsi protégé. Les recherches effectuées au cours de cette thèse ont mené à l’identification des films minces électrogreffés qui réduisent efficacement le frottement et l’usure des substrats métalliques en préservant des résistances électriques de contact satisfaisantes du même ordre qu’un contact direct or/or<br>In this thesis thin organic grafted films have been studied as lubrifiant for electrical contacts. Thin film were electrografted on gold which is currently used for the final metallic layer of some common low-level electrical connectors. Two families have been studied : the cathodic electrografted poly(methacrylate)s and the poly(phenylene)-like films obtained by the reduction of aromatic diazonium salts. Composite films have also been fabricated between the electrografted poly(methacrylate) and carbon nanotubes or conducting polymers in order to ameliorate electrical conduction properties. First the physical chemistry properties of the film have been studied and in particular the electrochemical behaviour of the molecules used as building blocks, the electrochemical grafting of the molecules used as building blocks, the electrochemical grafting of the films and the film surface physical chemistry properties. Then tribological and electrical tests were effectuated to study the lubrication effect obtained upon substrate functionalization by the organic films and their effect on the contact electrical resistance. The researches effectuated during this thesis allowed for the identification of thin electrografted films capable of effective reduction of friction and wear of gold substrates preserving low electrical resistances
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Schäfer, Christian Martin. "Towards organic-inirganic hybrid thin films deposited by ALD/MLD." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22267.
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Mestrado em Química<br>A técnica de deposição por camada atómica (ALD) permite a deposição de filmes finos em fase de vapor de alta qualidade com um controlo de espessura à nano-escala. No presente trabalho foi demonstrado a deposição de filmes finos de óxido de zinco (ZnO) por ALD de elevada uniformidade em diferentes substratos, incluído nano-estruturas como por exemplo, nanotubos de carbono.
Demonstrou-se por difracção de raio-X que o processo de deposição do ZnO originou a formação da estrutura da hexagonal, na fase wurtzite, com uma taxa de crescimento por ciclo de 1.9 Å. A deposição de filmes finos de natureza inorgânica (e.g. óxidos metálicos) por ALD está bem estabelecida contrariamente à emergente deposição por camada molecular (MLD) de filmes finos puramente orgânicos. Actualmente, a combinação de ALD/MLD começa a ganhar importância na criação de estruturas híbridas do tipo orgânica-inorgânicas. Nomeadamente, através da selecção adequada dos precursores, é possível obter diferentes arquitecturas funcionais em forma de filme fino, incluindo nano-laminados, superestruturas e redes metalo-orgânicas (MOFs) nano-porosas. A deposição de MOFs por ALD/MLD surge como uma alternativa para superar as desvantagens dos métodos convencionais de deposição de filmes finos baseados em soluções. Este trabalho contempla também a revisão da literatura no que diz respeito à síntese de este tipo de filmes finos obtidos em fase de vapor. Procedeu-se à reprodução dos resultados da literatura tendo como objectivo a síntese de filmes finos híbridos orgânico-inorgânicos (e.g. MOFs). Numa primeira fase efectuou-se a transformação vapor-sólido de um filme de ZnO crescido por ALD por exposição ao vapor de 2-metilimidazol. Posteriormente usou-se um processo ALD/MLD com o propósito de depositar uma estrutura do tipo zeólito (ZIF-8) a partir da reacção do dietilzinco (DEZ) e o 2-metilimidazol. Finalmente realizou-se a síntese de dois sistemas de filmes finos híbridos com base no ácido tereftálico como precursor orgânico e os seguintes precursores organometálicos: DEZ e Eu(TMHD)3. Para o caso do sistema DEZ/TPA, a formação da ligação Zn-TP nos filmes híbridos, foi observada por espectroscopia de FTIR<br>Atomic layer deposition is a state-of-the-art vapor phase deposition method for the creation of high quality thin films with nanoscale thickness control. As demonstrated in this work by the deposition of ZnO with a home-built reactor, ALD enables uniform and conformal film deposition even on complex nanostructures like carbon nanotubes. Deposition of hexagonal wurtzite ZnO proven by GIXRD with a growth-per-cycle of 1.9 Å, determined from XRR thickness measurements, was demonstrated. While the ALD synthesis of inorganic thin films, such as metal oxides is widely established, the organic counterpart molecular layer deposition (MLD) is still emerging. Recently, combining ALD/MLD has attracted great interest for the creation of organic-inorganic hybrid structures. By choice and adaptation of suitable precursors a great versatility of functional thin film architectures is achievable, spanning from novel multilayer nanolaminates and superstructures for thermoelectrics, over luminescent lanthanide hybrid films for optical application to even crystalline, nanoporous metal-organic frameworks (MOFs) as low-κ dielectrics in microdevices. Especially in the field of MOFs, a clean and precise synthesis route by ALD/MLD is desirable for device implementation in order to overcome the drawbacks of conventional, solution-based thin film deposition techniques. In this work, recent advances towards these vapor-processed hybrids are reviewed. Then, the reproduction of literature results leading to the deposition of organic-inorganic hybrid thin films (e.g. MOFs) was studied. The feasibility of a vapor-solid transformation of a sacrificial ALD-grown ZnO film by exposure to 2-methylimidazole (HMIM) and a direct ALD/MLD method using HMIM and diethylzinc (DEZ) towards a zeolitic imidazole framework (ZIF-8) have been attempted. Finally, the synthesis of two different hybrid films was studied involving the organic precursor terephthalic acid (TPA) combined with the organometallic precursors DEZ or Eu(TMHD)3. In case of the DEZ/TPA system, the deposition of a hybrid thin film with Zn-terephthalate bondings was evidenced by FTIR spectroscopy.
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Back, Andrew Scott. "Molecular architecture of ordered thin films of crystalline organic dyes." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282491.
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The factors which determine the growth mode and molecular architecture of vacuum deposited organic thin films on single crystalline substrates were investigated. Specifically, the relative importance of layer planes in the bulk structure, lattice matching between the overlayer and substrate, topographic direction by the substrate, and specific molecule-substrate interactions, in determining the growth mode were examined. The majority of the molecules studied here (ClAlPc, F₁₆ZnPc, PTCDA, C4-PTCDI, and C5-PTCDI) exhibited layer planes in their bulk structures, however, the molecular plane is coincident with the layer plane only for PTCDA and ClAlPc. ClAlPc and F₁₆ZnPc were found to adopt different flat-lying commensurate square lattices on the Cu(100) surface. In both cases, the flat-lying orientation of the molecules was dictated by specific molecule-substrate interactions, while the orientation of the lattice was dictated by lattice matching with the substrate. ClAlPc was also able to adopt an incommensurate centered rectangular lattice whose orientation was directed by alignment along step edges. Fluorescence investigation of submonolayer PTCDA and PTCDI films on alkali halide substrates demonstrated the great potential of fluorescence spectroscopy as a means of monitoring film growth. PTCDA was found to adopt a flat-lying orientation on NaCl, KCl, and KBr, while a flat-lying orientation of the PTCDI molecules was determined by the strength of the molecule-substrate interactions. From these measurements, the relative interaction strengths of the substrates were determined to be KCl > KBr > NaCl. IR dichroism showed that the expected growth along the layer planes was found only to occur for PTCDA, due to the coincidence of the layer and molecular planes. IR spectroscopy also revealed that a new polymorph of C5-PTCDI had been formed on these surfaces. These studies showed that the relative importance of the factors in determining the molecular architecture adopted within the first 1-2 MLE of a film are: (1) molecule-substrate interaction, (2) lattice matching, (3) topographic direction, (4) layer planes in the bulk structure. In addition the use of fluorescence spectroscopy to probe the evolution of vacuum deposited films was significantly advanced.
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Burrill, KimNgan. "Exciton Coherence in 1D Phthalocyanine Based Organic Crystalline Thin Films." ScholarWorks @ UVM, 2020. https://scholarworks.uvm.edu/graddis/1176.
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Quantum coherence plays a vital role in the excitonic properties of organic semiconductors. Several theoretical and experimental studies have shown an unprecedented role of coherence in charge transfer and transport processes, which in turn can improve the performance of electronic devices. Specifically, an enhancement of exciton coherence size can result in fast energy transport and efficient charge separation. The ability to tailor the design and performance of organic electronics based on exciton coherence effects represents the possibility of ultrafast electronic applications in communication and information technology.
The objective of this thesis is the excitonic coherence studies of 1D crystalline thin films of phthalocyanine-based organic semiconductors using steady-state and time-resolved photoluminescence spectroscopy (TRPL). One of the main focuses of this work is on investigating the correlation of intermolecular interactions, $\pi$ orbital overlap and dynamic disorders on the excitonic coherent behaviors in crystalline thin films of various phthalocyanine derivatives (i.e. H$_2$TPP, H$_2$OBPc, H$_2$OCPc, and H$_2$OBNc). Specifically, coherence lengths, exciton-phonon coupling strengths and the nearest neighbor (NN) interaction strengths are determined via: (1) the PL ratio of the excitonic coherence transition and its first vibrational replica and (2) the temperature evolution of radiative recombination lifetimes of coherent excitons. This study showed that the optimum coherence size and the robustness of excitonic coherence can be achieved by a complex interplay between NN interaction, vibrational energies and the coupling to vibrational modes. In particular, it is shown that the shortest NN distance does not ensure the achievement of maximum coherence length within the four investigated phthalocyanine species. Instead, the largest coherence length is measured in the octabutoxy derivative, where the saddle shape of the molecule and crystalline packing results in weaker coupling to the acoustic phonons modes despite having larger intermolecular NN distance. In addition, the effect of static and dynamic disorders on the behavior of exciton coherence is explored by alloying two phthalocyanine derivatives that are close in band gap energies and possess large coherence lengths, H$_2$OBPc and H$_2$OBNc. This study demonstrated the successful tuning of exciton coherence lengths and excitonic parameters in organic analogues of semiconductor alloys, H$_2$OBNc$_x$H$_2$OBPc$_{1-x}$. Furthermore, the correlation of exciton-phonon coupling and radiative recombination rate of coherent excitons with increasing alloy concentration or static disorders are successfully revealed.
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Lanzilotto, Valeria. "Self-assembling and charge transfer properties of thin organic films." Doctoral thesis, Università degli studi di Trieste, 2012. http://hdl.handle.net/10077/7362.
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2010/2011<br>In the present thesis I dealt the issue of molecular ordering and charge transfer at two types of organic-inorganic interfaces that are representative of the basic constituents of an organic electron device. I investigated i.) the influence of a selected dielectric surface on the ordering of an overlayer of several organic molecules and ii.) the electronic transport properties of a single molecular junction with a metal electrode.
Both systems have been characterized by a structural and electronic point of view. Among the techniques available for structural investigation, I made extensive use of Helium Atom Scattering (HAS) and Scanning Tunneling Microscopy (STM). The electronic properties, with particular emphasis to the charge transfer, have been addressed by two methods chosen according to the dimensionality of the system under consideration. For the charge transfer at laterally extended interfaces I used synchrotron based techniques, like Resonant Photoemssion Spectroscopy (RPES), while for the charge transport through a single molecule I used and developed the STM-based break junction technique (STM-BJ).
For the first type of interface, I focused on the coupling between the TiO2(110)-1x1 surface and different organic semiconductor molecules: C60, pentacene, perylene-tetracarboxilic-acid-diimide (PTCDI) and perylene. The strong anisotropy of the substrate has been found to drive the adsorption geometry of the molecules leading to the formation of ordered phases (at least for the first layer). In particular pentacene, PTCDI and perylene (polycyclic aromatic hydrocarbons, PAHs) display a common self-assembly mechanism, where the molecules lay on the surface with their long axis oriented parallel to the [001] substrate direction. In the transverse direction [1-10] these molecules are observed to match the substrate periodicity by tilting the molecular plane around the long axis by an angle that depends on the molecular width. Nevertheless the molecule-to-substrate interaction is very weak as indicated by the molecular electronic structure, which is observed by X-ray spectroscopy to remain mostly unperturbed in the first molecular layer. Only PTCDI bears a major interaction with the TiO2(110)-1x1 surface, but confined to the molecular orbitals closest to the gap. The main experimental evidence of this interaction is the appearance of a new molecular filled state in the valence band region close to the Fermi level. By a combined RPES and NEXAFS study we have found that this new electronic state is due to the charge transfer occurring from the substrate Ti defect state (i.e. the excess of electrons associated with oxygen vacancies) to the
lowest unoccupied molecular orbital (LUMO).
For the second type of hybrid interface, instead, I exploited the nitrogen-link chemistry in order to bridge a phthalocyanine to two gold electrodes and to measure its conductance. In particular, by using the Tetraaza-Cu-Phthalocyanine
I investigated the pyridine-gold bond that is relatively weak and insensitive to the local structure, a fundamental requirement for the establishment of well defined and stable transport properties. The weak interaction between the molecule and a representative metal electrode, namely the Au(100) surface, has been confirmed by spectroscopic and STM experiments. At RT the molecules have been found to diffuse on the surface and only at LT (55 K) they can be observed to self-organize into large molecular domains. On these domains, reliable and reproducible single molecule conductance measurements have been performed by using the STM-based break junction method. The conductance value obtained for the Tetraaza-Cu-Phthalocyanine (7x10-4 G0) has been rationalized in terms of the molecular length and degree of conjugation, as well as by correlation to the energy level alignment at the junction.<br>XXIV Ciclo<br>1984
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Turangan, Nikka Maria Joezar. "Synthesis and characterisation of covalent organic frameworks as thin films." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/129108/1/Nikka_Turangan_Thesis.pdf.
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This research tackles the challenge of synthesising a highly porous material, known as a covalent organic framework, as a self-supporting membrane, with potential applications in gas and chemical filtration and storage. Micrometer-thick freestanding membranes were successfully synthesised in this project through two different techniques, which allowed selection of the chemical, physical and mechanical properties of the membrane.
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Patil, V. J. "Electrostatically controlled formation of nanocomposite thin films with organic matrices." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1999. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2931.
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Liu, Xiao. "Elaboration and characterization of organic semiconducting thin films for optoelectronics." Electronic Thesis or Diss., Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2020SORUS205.pdf.
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Ce travail de thèse a pour but l’élaboration et la caractérisation de film minces semi-conducteurs à partir de différents matériaux p-conjugués (DAL1, BTBT, C8-BTBT-C8, C10-PBT etd iI(T2)2) pour des applications en optoélectronique. L’objectif général a porté sur l’optimisation de leurs méthodes de fabrication, de manière à améliorer les performances des composants électroniques correspondant (transistors à effet de champs et diodes électroluminescentes organiques)<br>This PhD work aims at the elaboration and characterization of organic semiconducting thin films based on different π-conjugated materials (DAL1, BTBT, C8-BTBT-C8, C10-PBT and iI(T2)2) for organic optoelectronics applications. The general goal is to optimize their fabrication methods in order to maximize their device performances of the corresponding optoelectronic devices (Organic field effect transistors and Organic light emitting diodes)
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Cai, Li-Rong. "Organic-inorganic layer-by-layer self-assembled multilayer films : preparation, characterization and applications /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202004%20CAI.
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Shamba, Precious. "MOCVD growth and electrical characterisation of InAs thin films." Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/706.
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In this work, a systematic study relating the surface morphologies, electrical and structural properties of both doped and undoped InAs and InAsSb epitaxial films grown by metalorganic chemical vapour deposition (MOCVD) was undertaken. A comparative study using TBAs and AsH3 as the group V source in the growth of InAs revealed a considerable improvement, primarily in the electrical properties of InAs grown using TBAs with no significant difference in the surface morphology. InAs layers grown using TBAs, exhibited superior 77 K mobilities of up to 46 000 cm2/Vs, exceeding the best MOCVD data to date. The feasibility of tetraethyl tin (TESn) as an n-type dopant in InAs was to our knowledge investigated for the first time. The incorporation efficiency of this dopant was extensively studied as a function of substrate temperature, V/III ratio, substrate orientation and TESn flow rate. Results from this study show that the doping efficiency is temperature dependent and is not influenced by a variation of the V/III ratio or substrate orientation. Furthermore, Sn doping concentrations could be controlled over 2 orders of magnitude ranging between 2.7 x 1017 and 4.7 x 1019 cm-3 with 77 K mobilities ranging from 12 000 to 1300 cm2/Vs. The electrical properties of zinc doped InAs employing dimethyl zinc (DMZn) as the ptype dopant, were studied as a function of V/III ratio and substrate orientation. The effect of a variation of these parameters on the structural properties and surface morphology of InAs is also reported. The substrate orientation appears to have no influence on the Zn incorporation. An increase in Zn incorporation resulted in a deterioration of both the surface morphology and structural quality of the InAs layers. The incorporation efficiency of DMZn in InAsSb was studied as a function of growth temperature, V/III ratio and DMZn flow rate. A higher Zn incorporation was observed in InAsSb epitaxial layers grown at a lower temperature and V/III ratio as opposed to the layers grown at a higher temperature and V/III ratio. This study also revealed that the use of DMZn caused a dopant memory effect. A two-layer model proposed by Nedoluha and Koch (1952) was used to simulate the Hall measurements of Zn doped InAs and InAsSb in order to correct the shortcomings of conventional Hall measurements in determining the electrical properties exhibited by these materials.
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Wilde, Jason N. "Optical sensing of organic vapours using Langmuir-Blodgett films." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/4763/.
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This thesis describes hydrocarbon vapour sensing using Langmuir-Blodgett films prepared from: a co-ordination polymer; substituted phthalocyanines containing copper and zinc as the central metal ions; and a polysiloxane. The physical and chemical properties of the co-ordination polymer, 5,5'-methylenebis (N- hexadecylsalicylidenamine), at the air water interface were investigated using Brewster angle microscopy and surface pressure versus area measurements. Langmuir-Blodgett films were built-up on a variety of substrates. The addition of copper acetate to the subphase caused a change in both the physical and optical properties of the Langmuir- Blodgett layers. Film thickness data suggest that a true monolayer (thickness ca 2 nm) is only formed under these conditions. The multilayer films were studied using X-ray diffraction, UV/Visible spectroscopy, ellipsometry, surface plasmon resonance, surface profiling and electron spin resonance. The response of each film when exposed to, benzene, toluene, ethanol and water vapours were recorded. Two optical systems were used, both based on surface plasmon resonance. The first incorporated a silicon photodiode to record the intensity of the reflected light. The second was similar to that of surface plasmon microscopy, using a charge coupled device camera to monitor the reflected light intensity from the Langmuir-Blodgett film/metal interface. The co-ordination polymer was found to be most sensitive to benzene and could reliably detect concentrations of this vapour down to 100 vapour parts per million. Data obtained when the co-ordination polymer was exposed to benzene and water vapour (using the latter system) were presented to a neural network for recognition.
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Chen, Yi. "Organic thin film transistors with mono-crystalline rubrene films by horizontal hot wall deposition." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66699.
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As promising candidates for future low-cost and flexible display applications, organic thin film transistors (OTFTs) have attracted considerable research interests for the past two decades. Recent advances in organic semiconductor theory and organic film growth/deposition techniques have resulted in OTFTs based on single crystalline organic films with performance approaching or even exceeding the present day's dominant amorphous silicon TFT technology. In this work, efforts have been made to explore suitable methods for the fabrication of thin film transistors based on high mobility organic semiconductors, such as rubrene and pentacene. In the early stage of this work, OTFTs with rubrene single crystals grown by PVT (Physical Vapor Transport) method were fabricated and measured with u-max,eff = 1.07 cm^2/V-s, ION/IOFF ~ 10^5 and VT = 0 V. However, it was noticed that these rubrene films are usually fragile and the adhesion to the substrates is often poor, leading to low reproducibility of functional devices. Hence, direct deposition of organic thin films to the substrates is a necessary measure to solve these problems. In this work, a horizontal hot wall deposition (HHWD) method has been developed to directly deposit high quality rubrene films onto the substrate under low pressure (P ~ 10^-6 torr). The resulted films were continuous with good coverage, however different structural phases from amorphous to near mono-crystalline were present. Through intensive studies on the film morphology and crystallinity of rubrene films deposited under different conditions, it is concluded that various factors can greatly affect the organic thin film growth, including surface treatment conditions, substrate orientations, source evaporation temperatures as well as substrate temperatures. Under the optimal deposition conditions, rubrene films are mono-crystalline with planar structure and grain sizes as large as 0.1 x 2<br>En raison de leur potentiel de pouvoir contribuer à la diminution des coûts dans la fabrication des écrans plats flexibles, les transistors à couche mince organiques (OTFTs) ont attiré énormément d'intérêts dans les dernières décennies.Les avances récentes dans les théories sur les semiconducteurs organiques ainsi que celles sur les techniques de déposition et de croissance ont résulté au développement des OTFTs basés sur des couches organiques monocrystallines avec des performances approchant et même excédant celles dérivées des techniques de fabrication de TFTs de silicium amorphe qui sont couramment dominantes en industrie. Dans cette étude, des efforts ont étés mis pour explorer des méthodes convenables à la fabrication des transistors couches minces basés sur des semiconducteurs organiques à mobilité élevée comme le rubrène et le pentacène.Dans les premières étapes de cette étude, des OTFTs avec du rubrène monocrystalline dont la croissance a été atteinte par la méthode PVT ont été fabriqués et mesurés avec une max,eff = 1.07 cm^2/V-s, un ION/IOFF ~ 10^5 et un VT = 0 V. Il est à noter que ces couches de rubrène sont typiquement fragiles et l'adhésion aux substrats était souvent faible ce qui résultait en une reproductibilité réduite de dispositifs opérationnels. C'est alors que la déposition directe des couches minces organiques aux substrats devient une mesure nécessaire pour résoudre ces problèmes. Dans cette étude, une méthode de déposition à paroi chaude horizontale (HHWD) a été développée pour la déposition directe sous basse pression (P ~ 10^-6 torr)des couches de rubrène à haute qualité sur des substrats. Les couches résultantes sont continues avec une bonne couverture, tandis que des différentes phases structurelles amorphes et monocrystallines sont présentes. Par des études intensives sur la morphologie des couches et$