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1
Hein, Moritz. "Organic Thin-Film Transistors." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-167894.
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Organic thin film transistors (OTFT) are a key active devices of future organic electronic circuits. The biggest advantages of organic electronics are the potential for cheep production and the enabling of new applications for light, bendable or transparent devices. These benefits are offered by a wide spectrum of various molecules and polymers that are optimized for different purpose.
In this work, several interesting organic semiconductors are compared as well as transistor geometries and processing steps. In a cooperation with an industrial partner, test series of transistors are produced that are intensively characterized and used as a basis for later device simulation. Therefore, among others 4-point-probe measurements are used for a potential mapping of the transistor channel and via transfer line method the contact resistance is measured in a temperature range between 173 and 353 K.
From later comparison with the simulation models, it appears that the geometrical resistance is actually more important for the transistor performance than the resistance of charge-carrier injection at the electrodes. The charge-carrier mobility is detailed evaluated and discussed. Within the observed temperature range a Arrhenius-like thermal activation of the charge- carrier transport is determined with an activation energy of 170 meV. Furthermore, a dependence of the electric field-strength of a Poole-Frenkel type is found with a Poole-Frenkel factor of about 4.9 × 10E−4 (V/m) −0.5 that is especially important for transistors with small channel length. With these two considerations, already a good agreement between device simulation and measurement data is reached. In a detailed discussion of the dependence on the charge-carrier density and from comparison with established the charge-carrier mobility models, an exponential density of states could be estimated for the organic semiconductor.
However, reliability of OTFTs remains one of the most challenging hurdles to be understood and resolved for broad commercial applications. In particular, bias-stress is identified as the key instability under operation for numerous OTFT devices and interfaces. In this work, a novel approach is presented that allows controlling and significantly alleviating the bias-stress effect by using molecular doping at low concentrations. For pentacene as semiconductor and SiO2 as gate oxide, we are able to reduce the time constant of degradation by three orders of magnitude. The effect of molecular doping on the bias-stress is explained in terms of the shift of Fermi level and, thus, exponentially reduced proton generation at the pentacene/oxide interface. For transistors prepared in cooperation with the industrial partner, a second effect is observed that can be explained by a model considering a ferroelectric process in the dielectric and counteracts the bias-stress behavior.
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Zhu, Wen Wei. "Organic thin film transistors." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19597.
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Organic thin film transistors (OTFTs) have been fabricated using four different semiconducting polymers: poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), polyhedral oligomeric silsesquioxanes (POSS) poly (2-methoxy-5-(2'-ethyl-hexyloxy)-l,4-phenylene vinylene) (MEH-PPV-POSS), poly[N-(3-methylphenyl)-N,N-diphenylamine-4,4'-diyl] (poly-TPD), and polyhedral oligomeric silsesquioxanes (POSS) poly (N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine (poly-TPD-POSS). These OTFTs were fabricated on heavily doped «-type silicon wafers with thermally grown silicon dioxide layer was used as gate insulator. Except for MEH-PPV, the OTFTs studied in this work are the first for the above organic semiconductor materials. From results of current-voltage measurements, it was observed that the present OTFTs showed I-V characteristics of typical /^-channel thin film transistors. Some of the fabricated OTFTs showed performance with relatively large field-effect mobilities (>10~4 cm2 V"1 s"1). The mobility of semiconducting polymer with polyhedral oligomeric silsesquioxanes (POSS) was at least one order of magnitude larger than that of parent polymer without the POSS. The largest mobility value was obtained on poly-TPD-POSS (4.34 x 10"4 cm2 V"1 s"1) in room atmosphere and at room temperature. Thermal annealing under different conditions was carried out on the polymers and the effects on carrier field-effect mobilities were examined. The thermal annealing can increase slightly the field-effect mobilities of the polymers without POSS. However, no significant effect was observed on the field-effect mobilities of the polymers with POSS.
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Stott, J. E. "Organic thin film transistors : integration challenges." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1393282/.
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This thesis considers some of the requirements and challenges in the eld of organic thin lm transistors (OTFTs), from the standpoint of large scale integration using low temperature plastic compatible processes. A combination of processes and materials for use in the fabrication of OTFTs is developed, yielding device performance comparable with the state of the art for bottom-contact, bottom-gate, organic small molecule thin lm transistors. High quality silicon nitride (SiNx) gate dielectric material is developed using plasma enhanced chemical vapour deposition (PECVD) at a low temperature (150 C) compatible with plastic substrates. A variety of high quality lms are developed, allowing an investigation into the impact of changes in SiNx composition on OTFT performance. Surface modi cation strategies on SiNx substrates are considered, leading to almost an order of magnitude enhancement in OTFT performance, suggesting a suitable device architecture for large scale integration, and exploitation of novel organic material properties. We then examine organic semiconductor nanowire devices, which have begun to emerge as a new and exciting class of device in recent years. This work explores the possibilities of combining traditional thin lm transistor fabrication techniques with novel organic nanowires and examines the resultant transistor device behaviour. Two-dimensional arrays of nanowire devices are analysed, demonstrating the suitability of devices for large area applications. The combination of a large area and plastic compatible, low temperature dielectric with well known organic semiconductors in thin lm devices suggests that the integration of novel organic nanowires could provide an exciting performance enhancement over traditional OTFT devices.
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Herlogsson, Lars. "Electrolyte-Gated Organic Thin-Film Transistors." Doctoral thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69636.
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There has been a remarkable progress in the development of organic electronic materials since the discovery of conducting polymers more than three decades ago. Many of these materials can be processed from solution, in the form as inks. This allows for using traditional high-volume printing techniques for manufacturing of organic electronic devices on various flexible surfaces at low cost. Many of the envisioned applications will use printed batteries, organic solar cells or electromagnetic coupling for powering. This requires that the included devices are power efficient and can operate at low voltages. This thesis is focused on organic thin-film transistors that employ electrolytes as gate insulators. The high capacitance of the electrolyte layers allows the transistors to operate at very low voltages, at only 1 V. Polyanion-gated p-channel transistors and polycation-gated n-channel transistors are demonstrated. The mobile ions in the respective polyelectrolyte are attracted towards the gate electrode during transistor operation, while the polymer ions create a stable interface with the charged semiconductor channel. This suppresses electrochemical doping of the semiconductor bulk, which enables the transistors to fully operate in the field-effect mode. As a result, the transistors display relatively fast switching (≤ 100 µs). Interestingly, the switching speed of the transistors saturates as the channel length is reduced. This deviation from the downscaling rule is explained by that the ionic relaxation in the electrolyte limits the channel formation rather than the electronic transport in the semiconductor. Moreover, both unipolar and complementary integrated circuits based on polyelectrolyte-gated transistors are demonstrated. The complementary circuits operate at supply voltages down to 0.2 V, have a static power consumption of less than 2.5 nW per gate and display signal propagation delays down to 0.26 ms per stage. Hence, polyelectrolyte-gated circuits hold great promise for printed electronics applications driven by low-voltage and low-capacity power sources.
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Tiefenbruck, Laura C. (Laura Christine). "Visible spectrometer utilizing organic thin film absorption." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33760.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 133-134).
In this thesis, I modeled and developed a spectrometer for the visible wavelength spectrum, based on absorption characteristics of organic thin films. The device uses fundamental principles of linear algebra to reconstruct spectral components of a signal from the transmission through an organic thin film. Best possible performance of the device is characterized, effects of noise and filtering techniques are observed, and results from several organic films are tested. The implemented device is optimized for cost, spectral reconstruction quality is tested, and guidelines for optimal device performance are proposed.
by Laura C. Tiefenbruck.
S.M.
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Wu, Xin. "TiO2 Thin Film Interlayer for Organic Photovoltaics." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/582369.
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TiO2 films as electron collecting interlayers are important in determining the efficiency of organic photovoltaics (OPVs). Various methods of film deposition have been explored, and they revealed the tradeoff between pinhole free coverage (large shunt resistance) and small film thickness (small series resistance). It is hypothesized that atomic layer deposition (ALD) with its self-limiting nature and sub-nanometer level control would be able to circumvent this problem and provide TiO2 films of pinhole free coverage and small thickness. TiO2 films made by chemical vapor deposition (CVD) and ALD were investigated and compared. Conductive atomic force microscopy (CAFM) was used to characterize film morphology and conductivity. X-ray photoelectron spectroscopy (XPS) was utilized to analyze film composition and chemical state. Cyclic voltammetry (CV) was able to reveal the hole blocking capability of films. Finally, organic photovoltaic devices were made with different TiO2 films to reveal the relationship between device property and film characteristic. It is found that both CVD and ALD created TiO2 films with Ti4+ species containing oxygen from hydroxyl groups. They both showed conformal coverage of the electrode via CAFM and CV measurements, and clearly ALD method achieved this with a thinner film and smaller series resistance. This work provided the evidence of effective and surprising capabilities of electron harvesting and hole blocking of ultrathin ALD TiO2 films for OPVs.
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Yoshiikawa, Osamu. "Studies on organic thin film solar cells." Kyoto University, 2009. http://hdl.handle.net/2433/123895.
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Kyoto University (京都大学)0048
新制・課程博士
博士(エネルギー科学)
甲第14742号
エネ博第195号
新制||エネ||44(附属図書館)
UT51-2009-D454
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)教授 八尾 健, 教授 石原 慶一, 教授 辻井 敬亘
学位規則第4条第1項該当
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Muckley, Eric S. "Optimization of film morphology for the performance of organic thin film solar cells." Thesis, California State University, Long Beach, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1523341.
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The power conversion efficiency of organic thin film solar cells must be improved before they can become commercially competitive alternatives to silicon-based photovoltaics. Exciton diffusion and charge carrier migration in organic films are strongly influenced by film morphology, which can be controlled by the substrate temperature during film growth. Zinc-phthalocyaninelbuckminsterfullerene bilayer film devices are fabricated with substrate temperatures between 25°C and 224°C and their solar cell performance is investigated here. The device open-circuit voltage, efficiency, and fill factor all exhibit peaks when films are grown at temperatures between 160°C and 180°C, which is likely a result of both the increase in shunt resistance and reduction in undesirable back diode effects which occur between l00°C and 180°C. The device performance can also be attributed to changes in the film crystallite size, roughness, and abundance of pinholes, as well as the occurrence of crystalline phase transitions which occur in both zinc-phthalocyanine and buckminsterfullerene between 150°C and 200°C. The unusually high open-circuit voltage (1.2 V), low short-circuit current density (0.03 mA/cm2), and low device efficiency (0.04%) reported here are reminiscent of single layer phthalocyanine-based Schottky solar cells, which suggests that pinholes in bilayer film devices can effectively lead to the formation of Schottky diodes.
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Chen, Yi 1974. "Organic thin film transistors based on conjugated polymers." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81533.
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Thin film transistors with different polymers (PTFTs) as active channel layers have been fabricated and studied in this work. Three different fabrication procedures were used to fabricate long and short channel PTFTs on silicon substrates and long channel PTFTs on glass substrates. It has been shown that the success rate of fabrication of PTFTs on glass substrates with anodic Al 2O3 gate dielectrics is higher than that on silicon substrates with thermally grown SiO2 gate dielectrics.The characteristics of PTFTs fabricated using several polymers were studied. Among them, the ones based on regioregualr poly[3-hexylthiophene-2.5diy] (RR-P3HT) have the best performance with a field effect mobility (mueff) of about 0.01 cm2/V-s and ION/IOFF value of about 50 when doped with FeCl3. Results of measurement suggested that FeCl3 doping of P3HT could lead to a decrease of about 5 orders of magnitude in its contact resistance to Au electrodes, giving rise to two orders of magnitude increase of its apparent mobility. Therefore, it can be concluded that the contact resistances are the major limitation of performance of many PTFTs and need to be studied intensively in the future.
10
Hong, Y. "Characterization and modelling of organic thin film transistors." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604202.
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This dissertation addresses, through experiments and modelling, three important aspects of organic thin-film transistor (OTFT) device physics, namely: mechanisms of gate dielectric bias stress instabilities; correlation of transfer characteristics and pseudogap density of states of the organic semiconductor; mechanisms of source and drain contact resistance. Bias stress effects were investigated for two organic insulators (OI), PVP and PMMA, by employing a Si-SiO2-OI-metal capacitor structures. In the cross-linked poly(-vinylphenol) (PVP), it is found that the bias stress effect results from the motion of ionic impurities due to the presence of remnant water. A drift diffusion model is used to describe the ion transport and the resulting bias stress effect. In poly (methyl methacrylate) (PMMA), the physical origin of bias stress effect is twofold. In short time scale, β dielectric relaxation causes a big step of flat-band shift upon the change of bias polarity. Over long time scale, hole injection from the top electrode into PMMA causes nonsaturated flat-band shift which follows the diffusion-limited thermionic emission theory. Next, the author has studied the temperature dependence of transfer characteristic of poly (9,9-dioctylfluorene-co-bithiophene) (F8T2) TFT. A model based on an exponential distribution of density of states (DOS) above a conduction level is formulated and shows a good agreement with experimental gate voltage and temperature dependence of the channel current. The method allows to estimate the trap density and correlate it with the TFT fabrication conditions. Finally, the author has examined the contact effects in Au electrode bottom-contact pentacene TFT. Combination of 2-D modelling and experiments indicates that the poor contact is due to the injection barrier between the source contact and channel. The current-voltage characteristics of the source contact are extracted from the output characteristics.
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Zocco, Adam T. "Pentacene-based Organic Thin-film Transistors on Paper." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1382950881.
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Reig, Canyelles Marta. "Carbazole-Based Materials for Organic Thin-Film Transistors and Organic Light-Emitting Diodes." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/404560.
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This thesis deals with the preparation and characterization of novel organic semiconductors based on the carbazole heterocycle for electronic and optoelectronic applications, specifically to be studied as active layers in OTFTs and as emitting layers in OLEDs. Carbazole-based materials are recognised for their high thermal stability, high emission efficiencies and excellent hole-transporting properties associated to its electron-donating ability, which make of them promising candidates for OTFTs and OLEDs applications.
OLEDs have been studied extensively due to their promising applications in flat panel displays and solid-state lighting. However, further improvement of power efficiency and colour purity are still required to produce more efficient industrial devices. Thus, the first part of this thesis deals with the preparation of a series of carbazole-based blue emitters for their application as emitting layers in blue and in particular in deep-blue OLEDs. The extension of the π-conjugated carbazole system by preparing bicarbazole and tricarbazole derivatives afforded materials with the sought deep-blue emission properties in the solid state, which were modulated by the insertion of the ethynylene linker. OLED devices exhibited very low turn-on voltages and a maximum luminance as high as 1.4 x 104 cd m–2.
The second part of this thesis is focused on the development of new organic semiconductors with effective charge transport properties. In order to obtain new n-type or ambipolar materials, the hole-transporting behaviour of the electron-donating carbazole moiety was modified by the introduction of electron-withdrawing groups on its structure. As a first approach, the coupling of the carbazole heterocycle with the electron acceptor tris(2,4,6-trichlorophenyl)methyl radical (TTM) yielded ambipolar materials, whose charge-transporting properties were found to be dependent on the substitution patterns of the carbazole core. As a second approach, the introduction of the strong electron-withdrawing tricyanovinyl group on the carbazole core afforded a push-pull system with high electron affinity, resulting in materials with n-type or ambipolar behaviour as determined by TOF and OTFT measurements.
The last part of this thesis is focused on the preparation of a series of p-type carbazole related derivatives, in which the extension of the π-conjugated core was progressively varied in order to study its effect on the charge-transporting properties. Indolo[3,2-b]carbazole and triindole derivatives showed enhanced OTFT device performance with hole mobilities in the range of 10–3 to 0.1 cm2 V–1 s–1. In particular, N-trimethyltriindole exhibits a face-to-face molecular packing with π–π interactions, and an optimal perpendicular molecular disposition to the substrate surface as determined by XRD, that can be related to a more favourable charge transport in the OTFT devices. The introduction of long hexyl chains in the triindole core contributes with additional C–H···π interactions to those of π–π type between the triindole cores, enhancing the degree of molecular order in the thin films as reflected in the determined hole mobility, which was found to be the highest value of all the series with a value of 0.1 cm2 V–1 s–1.
The knowledge of the molecular packing and intermolecular interactions in the organic layers has been proved to be essential to rationalize the charge-transporting properties and it is shown here to be a useful tool to be considered on the design of new organic semiconductors.El desenvolupament de nous semiconductors orgànics amb capacitat de transport de càrrega presenta un gran interès per a la seva aplicació en transistors orgànics de capa prima (OTFTs), díodes emissors de llum orgànics (OLEDs) i cel·les solars orgàniques, entre d’altres. L’objectiu d’aquesta tesi és la preparació i caracterització de nous semiconductors orgànics basats en l’heterocicle carbazole i el seu estudi com a components en OTFTs i en OLEDs. En primer terme, aquesta tesi està centrada en la preparació de nous derivats del carbazole amb propietats luminescents en la zona del blau de l’espectre electromagnètic. En concret, es pretén modular les propietats òptiques del carbazole mitjançant l’extensió de la conjugació del seu nucli aromàtic per introducció de grups donadors d’electrons en la seva estructura, així com per la introducció del triple enllaç com a espaiador entre el nucli carbazole i els grups donadors d’electrons. L’estudi dels materials preparats com a capes emissores en OLEDs ha donat lloc a dispositius amb emissió a la zona del blau que han presentat una elevada luminància de fins a 1.4 x 104 cd m–2. La segona part de la tesi està enfocada en el desenvolupament de nous semiconductors orgànics basats en l’heterocicle carbazole i l’estudi de les seves propietats de transport de càrrega. Per tal de preparar nous semiconductors orgànics de tipus n o ambipolars, es pretén modificar les propietats de transport de forats del nucli carbazole mitjançant la introducció de grups atractors d’electrons en la seva estructura. Per una altra banda, s’ha preparat una sèrie de materials basats en el carbazole en què s’ha variat progressivament l’extensió del seu sistema conjugat, per tal d’obtenir derivats amb propietats de transport de forats efectives. Les propietats de transport de càrrega dels materials preparats s’han avaluat mitjançant la tècnica “time of flight” (TOF) i la preparació i mesura de OTFTs. S’han obtingut alts valors de mobilitat de forats de fins a 0.1 cm2 V–1 s–1 a partir de OTFTs basats en derivats del triindole. Els resultats obtinguts s’han correlacionat amb l’estructura molecular, el tipus d’empaquetament molecular, i amb el grau d’ordre i disposició de les molècules a les capes dels dispositius mitjançant estudis de difracció de raigs X i càlculs teòrics.
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Gleed, D. G. "Brillouin scattering from organic layers." Thesis, University of Exeter, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.232975.
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Roberson, Luke Bennett. "Understanding organic thin film properties for microelectronic organic field-effect transistors and solar cells." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-11072005-111532/.
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Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2006.Mohan Srinivasarao, Committee Member ; David Collard, Committee Member ; Uwe Bunz, Committee Member ; Art Janata, Committee Member ; Marcus Weck, Committee Member ; Laren Tolbert, Committee Chair.
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Kim, Jungbae. "Organic-inorganic hybrid thin film transistors and electronic circuits." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34683.
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Thin-film transistors (TFTs) capable of low-voltage and high-frequency operation will be required to reduce the power consumption of next generation electronic devices driven by microelectronic components such as inverters, ring oscillators, and backplane circuits for mobile displays. To produce high performance TFTs, transparent oxide-semiconductors are becoming an attractive alternative to hydrogenated amorphous silicon (a-Si:H)- and organic-based materials because of their high electron mobility vlaues and low processing temperatures, making them compatible with flexible substrates and opening the potential for low production costs. Practical electronic devices are expected to use p- and n-channel TFT-based complementary inverters to operate with low power consumption, high gain values, and high and balanced noise margins. The p- and n-channel TFTs should yield comparable output characteristics despite differences in the materials used to achieve such performance. However, most oxide semiconductors are n-type, and the only high performance, oxide-based TFTs demonstrated so far are all n-channel, which prevents the realization of complementary metal-oxide-semiconductor (CMOS) technologies.
On the other hand, ambipolar TFTs are very attractive microelectronic devices because, unlike unipolar transistors, they operate independently of the polarity of the gate voltage. This intrinsic property of ambipolar TFTs has the potential to lead to new paradigms in the design of analog and digital circuits. To date, ambipolar TFTs and their circuits, such as inverters, have shown very limited performance when compared with that obtained in unipolar TFTs. For instance, the electron and hole mobilities typically found in ambipolar TFTs (ATFTs) are, typically, at least an order of magnitude smaller than those found in unipolar TFTs. Furthermore, for a variety of circuits, ATFTs should provide balanced currents during p- and n-channel operations. Regardless of the selection of materials, achieving these basic transistor properties is a very challenging task with the use of current device geometries.
This dissertation presents research work performed on oxide TFTs, oxide TFT-based electronic circuits, organic-inorganic hybrid complementary inverters, organic-inorganic hybrid ambipolar TFTs, and ambipolar TFT-based complementary-like inverters in an attempt to overcome some of the current issues. The research performed first was to develop low-voltage and high-performance oxide TFTs, with an emphasis on n-channel oxide TFTs, using high-k and/or thin dielectrics as gate insulators. A high mobility electron transporting semiconductor, amorphous indium gallium zinc oxide (a-IGZO), was used as the n-channel active material. Such oxide TFTs were employed to demonstrate active matrix organic light emitting diode (AMOLED) display backplane circuits operating at low voltage.
Then, high-performance hybrid complementary inverters were developed using unipolar TFTs employing organic and inorganic semiconductors as p- and n-channel layers, respectively. An inorganic a-IGZO and pentacene, a widely used organic semiconductor, were used as the n- and p-channel semiconductors, respectively. By the integration of the p-channel organic and n-channel inorganic TFTs, high-gain complementary inverters with high and balanced noise margins were developed. A new approach to find the switching threshold voltage and the optimum value of the supply voltage to operate a complementary inverter was also proposed.
Furthermore, we proposed a co-planar channel geometry for the realization of high-performance ambipolar TFTs. Using non-overlapping horizontal channels of pentacene and a-IGZO, we demonstrate hybrid organic-inorganic ambipolar TFTs with channels that show electrical properties comparable to those found in unipolar TFTs with the same channel aspect ratios. A key characteristic of this co-planar channel ambipolar TFT geometry is that the onset of ambipolar operation is mediated by a new operating regime where one of the channels can reach saturation while the other channel remains off. This allows these ambipolar TFTs to reach high on-off current ratios approaching 104. With the new design flexibility we demonstrated organic-inorganic hybrid ambipolar TFT-based complementary-like inverters, on rigid and flexible substrates, that show a significant improvement over the performance found in previously reported complementary-like inverters. From a materials perspective, this work shows that future breakthroughs in the performance of unipolar n-channel and p-channel semiconductors could be directly transposed into ambipolar transistors and circuits. Hence, we expect that this geometry will provide new strategies for the realization of high-performance ambipolar TFTs and novel ambipolar microelectronic circuits.
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Wang, Yushu. "Thin-film trench capacitors for silicon and organic packages." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42741.
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The continuous trend towards mega-functional, high-performance and ultra-miniaturized system has been driving the need for advances in novel materials with superior properties leading to thin components, high-density interconnect substrates and interconnections. Power supply and management is becoming a critical bottleneck for the advances in such mega-functional systems because power components do not scale down with the rest of the system resulting in bulky and stand-alone power modules. Amongst the power components, thin film capacitors are considered the most challenging to integrate because of several manufacturability concerns. The challenges are related to process compatibility of high permittivity dielectrics with substrates and high surface area electrodes, yield, leakage and losses. This thesis focuses on novel thin film capacitor technologies that address some of these critical challenges.Thesis advisor has approved the addition of errata to this item. The abstract text in the metadata record has been modified to match the document text.
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Carlegrim, Elin. "Development of Organic-Based Thin Film Magnets for Spintronics." Doctoral thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-56262.
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In the growing field of spintronics, development of semiconducting magnets is a high priority. Organic-based molecular magnets are attractive candidates since their properties can be tailor-made by organic chemistry. Other advantages include low weight and low temperature processing. Vanadium tetracyanoethylene, V(TCNE)x, x~2, is particularly interesting since it is one of very few semiconducting magnets with magnetic ordering above room temperature. The aim of the research presented in this thesis was to prepare and characterize thin film organic-based magnets with focus on V(TCNE)x. Photoelectron and absorption spectroscopy studies were performed leading to a more complete picture of the electronic and chemical structure of the material. Depending on the preparation method of V(TCNE)x, the material contains varying amounts of disorder which among other things makes it very air sensitive. In this thesis, a new preparation method for organic-based magnets based on physical vapor deposition is presented and the first result shows that it generates less air sensitive V(TCNE)x than previous methods reported. A new spin valve design based on V(TCNE)x was proposed where the material delivers both spin-filtering and spin-transporting functionality, making use of its fully spin-polarized transport levels. In such devices, the interface of V(TCNE)x with ferromagnetic metals is of great importance and was hence studied. As vanadium ions always are very reactive towards oxygen, substituting vanadium by a less reactive ion would be desirable from both an interface engineering and device packaging perspective. Very few alternatives exist however that orders magnetically above room temperature. In order to find out what are the key design criteria for preparing thin film semiconducting room temperature magnets, we have begun to study systems which order magnetically much below room temperature and compared them with V(TCNE)x.
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Reinhardt, Yvonne Jeneke [Verfasser], and Eicke [Akademischer Betreuer] Weber. "Imaging and thin-film optics of organic solar cells." Freiburg : Universität, 2016. http://d-nb.info/1124005145/34.
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Jiang, Chen. "All-inkjet-printed low-voltage organic thin-film transistors." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/285012.
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This thesis presents the development of all-inkjet-printed low-voltage organic thin-film transistors. Organic thin-film transistors (OTFTs), taking advantage of low-temperature printability, mechanical flexibility, and multi-functionality, are promising for a wide range of emerging applications such as wearable electronics. Printed OTFTs provide great benefits in fabrication cost reduction, but they need a very high operating voltage and exhibit severe instability during storage and operation in ambient environment. In this study, all-inkjet-printed OTFTs with a low operating voltage of less than 3 V are demonstrated through reducing trap density in the fabricated devices. The transistors use 6,13-bis(triisopropylsilylethynyl)pentacene as the semiconductor, poly(4-vinylphenol) as the dielectric, silver as the electrodes, and CYTOP as the encapsulation. Several aspects of physical and chemical properties of polymer dielectrics are studied to achieve this goal, including cross-linking, wetting, and moisture affinity. Through the careful selection of device architecture and control of the inkjet-printing processes, the semiconductor-dielectric interface trap density of the fabricated OTFTs is significantly reduced. The applicability of this approach to different materials is also investigated and confirmed, including polyvinyl cinnamate as the dielectric, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene as the semiconductor, and anisole as the solvent for semiconductor inks. Based on the investigation of different materials, the characteristics and parameters of all-inkjet-printed OTFTs are optimised, demonstrating an ultra-steep subthreshold of 60.2 mV/decade approaching the theoretical limit and a low operating voltage of 1 V. In order to explore their feasibility in real-world applications, the stability of all-inkjet-printed OTFTs is investigated and the factors of instability are analysed. Based on these findings, the stability of the fabricated device is improved, such that the threshold voltage shift is less than 0.1 V in ambient environment storage for 3 months and operation for 1 hour. The electrical characteristics of OTFTs in the subthreshold regime are studied for analogue circuit design. Based on the developed low-voltage stable transistors, an ultra-low-power (< 1 nW) high-gain (> 200 V/V) amplifier is presented and utilised to detect electrophysiological signals from the human body.
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Coe-Sullivan, Seth (Seth Alexander). "Hybrid organic/quantum dot thin film structures and devices." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33935.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 157-169).
Organic light emitting diodes have undergone rapid advancement over the course of the past decade. Similarly, quantum dot synthesis has progressed to the point that room temperature highly efficient photoluminescence can be realized. It is the purpose of this work to utilize the beneficial properties of these two material sets in a robust light emitting device. New deposition techniques are necessary to the realization of this goal, enabling QD organic hybrids to be created in a quick and reliable manner compatible with known device fabrication methods. With these techniques, quantum dot light emitting devices are fabricated, measured, and analyzed. The devices are of high efficiency and color saturation, and provide us with a test bed for understanding the interactions between inorganic QDs and organic thin films.
by Seth Coe-Sullivan.
Ph.D.
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Ding, Ziqian. "Large area vacuum fabrication of organic thin-film transistors." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:e7decca4-14e3-47e7-85ca-0bb14755f282.
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A process has been developed to make the dielectric layer for organic thin-film transistors (OTFTs) in a roll-to-roll vacuum web coater environment. This dielectric layer combined with an organic semiconductor layer and metal layer deposited in vacuum allows a solvent-free process to make organic/inorganic multilayer structures for thin-film electronic devices on a flexible substrate at, potentially, high speed. The polymeric gate dielectric layers were fabricated by flash evaporation of acrylic monomers onto a polymer film with pre-patterned metal gates followed by radiation curing by electron beam, ultra-violent light (UV) or plasma. With a non-polar dielectric surface, charge carrier mobility (μ) of 1 cm2-V-1s-1; on/off curren ratio of 108, sub-threshold swing (SS) of 0.3 V/decade and saturated output curve were routinely achieved in dinaphtho-[2,3-b:2'3'-f]thieno[3,2-b]thiophene (DNTT) transistors with dielectric layer of tripropylene glycol diacrylate (TPGDA) of ~400 nm. Apart from the TPGDA, monomer formulas including 1,6-Hexanediol diacrylate (HDDA) as well as several commercial acrylic resins have been used to make the dielectric layer. The highest areal capacitance of 41nF-cm-2 was achieved with a pin-hole free film of less than 100 nm made of an acrylate mixture resin. A non-polar dielectric surface treatment layer has been developed based on flash evaporation of lauryl acrylate and HDDA mixture. The transistors with the buffer layer showed constant performance and a mobility fivefold greater than those of untreated samples. The effect of humidity, oxygen, and light during switching cycles of both pentacene and DNTT transistors were studied. Water and oxygen/illumination had a distinct effect on both pentacene and DNTT transistors. Oxygen leads to acceptor-like charge traps under illumination, which shifted the turn-on voltage (Vto) to more positive values. In contrast, water in transistors gave rise to donor-like charge traps, which shifted the Vto and the threshold voltage (VT) more negatively. The DNTT devices showed good stability in dry air without encapsulation, while pentacene transistors degraded with either repeating measurement or long term storage. A DNTT transistor with a PS-coated TPGDA dielectric layer showed stable drain current (Id) of ~105A under bias stress of the gate voltage (em>Vg) of -20V and the drain voltage (em>Vd) of -20V for at least 144 hours. The Vto shift after the stress was less than 5 V and was recoverable when the device was kept in dry air for a few days. Possible reasons for the Vto shift have been discussed.
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Vorona, Mikhail. "Anthracene-Based Molecules for Organic Thin-Film Transistor Integration." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41536.
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Organic electronics are devices based on semiconductors derived from carbon based molecules and polymers. These devices can be made flexible, lightweight and potentially inexpensive with the development of economies of scale. Specific examples of organic electronics include organic thin-film transistors (OTFTs), organic light-emitting diodes (OLEDs) and organic photovoltaic (OPVs). Anthracene-based semiconductors are materials that have generated great interest primarily because of their structural planarity, potential for strong intermolecular interactions, air stability and ideal frontier molecular orbital energy levels. In this thesis, we detail two publications that examined functionalized anthracene molecules integrated into OTFTs, along with their thermal, electrochemical and optical properties. We started by examining seven novel 9,10-anthracene-based molecules. It was found that functionalization of the 9,10-positions with different phenyl derivatives resulted in negligible variation in the optical properties with minor (±0.10 eV) changes in electrochemical behaviour, while the choice of phenyl derivative greatly affected the thermal stability whereby the decomposition temperatures (Td) varied by as much as 128 °C between certain functionalized derivatives. The findings suggested that functionalization of the 9,10-position of anthracene leads to an effective handle for tuning of the thermal stability while having little to no effect on the optical properties and the solid-state arrangement. We continued with the synthesis of several novel anthracene derivatives which were di-substituted at the 2,6-positions. It was found that 2,6-functionalization with various fluorinated phenyl derivatives led to negligible changes in the optical behaviour while influencing the electrochemical properties (±0.10 eV). Furthermore, the choice of fluorinated phenyl moiety had noticeable effects on melting point and thermal stability (ΔTm < 55 °C and ΔTd < 65 °C). OTFTs were fabricated and characterized using the 2,6-anthracene derivatives as the semiconducting layer. The addition of fluorine groups on the phenyl groups led to a transition from p-type behaviour to n-type behaviour in BGBC OTFTs. The results indicated that the choice of functional group as well as its functionalization location, at the 9,10- and 2,6-positions, can act as powerful handles to engineer high performance OTFTs.
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Morales-Vidal, Marta. "High performance thin film organic lasers for sensing applications." Doctoral thesis, Universidad de Alicante, 2015. http://hdl.handle.net/10045/63751.
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Garg, Akhilesh. "Organic Self-Assembled Films for Nonlinear Optics: Film Structure, Composition and Kinetics of Film Formation." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28872.
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Organic materials exhibiting second-order non-linear optical (NLO) properties are a key to the development of advanced electro-optic (EO) modulators used in fiber-optic communications system. This work addresses the fabrication and characterization of organic materials with NLO properties using a self-assembly approach by alternately dipping a charged substrate into positively and negatively charged polymers to build up layer-by-layer (LbL) films.
The effect of solution pH on the formation of LbL films fabricated using the polycation poly(allylamine hydrochloride) (PAH) and the polyanion poly{1-[p-(3–-carboxy-4–-hydroxyphenylazo)benzenesulfonamido]-1,2-ethandiyl} (PCBS) was studied using a quartz crystal microbalance with dissipation (QCM-D) monitoring, ellipsometry, absorbance, and second harmonic generation (SHG) measurements. PCBS has an azo-benzene chromophore side group that, when sufficiently oriented, results in measurable SHG. Films of PAH/PCBS fabricated at neutral pH where both PAH and PCBS are highly charged led to thin bilayers, ~1 nm, with a 1:1 molar ratio of PCBS:PAH. This molar ratio was found to be important for long-range polar ordering of PCBS in these films. Increasing the rate of convection was found to reduce the time required for complete adsorption of the polyion. This can have a significant impact on fabrication of films with high bilayer numbers.
A variation of the above technique, which involves adsorbing one of the constituents electrostatically and another covalently, was studied using PAH and a reactive dye, Procion Brown (PB), which has a significantly higher hyperpolarizability than PCBS. It was found that a high pH, ~10.5, was important for achieving covalent attachment of the PB to the underlying PAH films. This resulted in much higher SHG intensities compared to when PB was deposited pH at 8.5-9.5 where the attachment of PB was due to a combination of electrostatic and covalent interactions. QCM-D results for PAH/PB films revealed the presence of a high percentage of unreacted amine groups in the underlying PAH film. A rate constant value for PB attachment step to the underlying PAH was also calculated.
To enhance the SHG intensity of these films, silver nanoprisms were synthesized and deposited onto films using physisorption. An enhancement in the SHG intensity was observed for both PAH/PCBS and PAH/PB films.Ph. D.
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Maddela, Madhurima Ramadoss Ramesh. "Design of MEMS-based tunable antennas, organic transistors and MEMS-based organic control circuits." Auburn, Ala, 2008. http://repo.lib.auburn.edu/2007%20Fall%20Dissertations/Maddela_Madhurima_8.pdf.
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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.Master of Science
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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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Kim, Namsu. "Fabrication and characterization of thin-film encapsulation for organic electronics." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31772.
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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Samuel Graham; Committee Member: Bernard Kippelen; Committee Member: David McDowell; Committee Member: Sankar Nair; Committee Member: Suresh Sitaraman. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Marchetto, Helder. "High-resolution spectro-microscopic investigations of organic thin film growth." [S.l.] : [s.n.], 2006. http://www.diss.fu-berlin.de/2006/458/index.html.
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Kwan, Man-chi. "Mobility enhancement for organic thin-film transistors using nitridation method." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37181580.
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Chen, Yi-Ming, and 陳逸銘. "Organic thin film transistor." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/92956758326867871048.
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碩士國立臺灣大學
光電工程學研究所
95
Organic thin film transistors (OTFTs) have attracted much attention because of the advantages of low-cost, large-area and flexible-substrate capability which can be widely used in the applications such as radio frequency identification tags, electronic papers, and flexible display. Although a lot of research groups focus on organic material synthesis, a self sustained electrical model for such devices is far from perfect right now. To understand the electrochemistry of organic materials and find the solution of stabilities of organic materials, a complete modeling and research on DC and AC is needed. In this paper, we started our simulations from the basic current-voltage equations of a semiconductor metal-oxide-semiconductor (MOS) device to build the DC modeling and extract the parameters. Comparing the differences between the organic and semiconductor devices, we found that, in an OTFT, the current-voltage characteristics are quite different from that in a semiconductor-MOS, and we developed the petacene grain size model to explain the experiment. And we perform DC stress to investigate the stability of organic material. And we try to investigate the variations of physical and modeling parameters that respond to AC current changes. Therefore, starting from small signal and large signal AC models, we built up the macroscopic AC response models from carrier point of view, which is essential to AC modeling since the polystalline property of OTFTs hasn''t been considered in AC model previously. Furthermore, we perform AC stress test to study the device failure mechanism. The results will be helpful to identify better material and device structures. Finally, we carry out the quasi-stable C-V test in a pentacene OTFT. The quais-stable C-V is a low frequency test to realize carrier transport behaviors under different applied voltages, swing durations and gate channel sizes. Our results indicate that carrier trap and de-trap process will affect the C-V profiles under different stress.
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Vadakkepatt, Gautham Gopal. "Essays on Firm Growth and Survival as a Fortune 500 Firm." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8532.
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In this dissertation, I develop frameworks and models capturing the effects of marketing capital and R and D capital on firm growth and sustained membership in the Fortune 500 cohort. Drawing on the resource-based view (RBV) of the firm and industrial organization theories, in the first essay, I develop hypotheses on the relationships among a firm's marketing capital, R and D capital, key firm-specific and industry-specific factors and survival as a Fortune 500 firm. I test these hypotheses using a proportional hazard model on a uniquely compiled large panel data set of manufacturing Fortune 500 firms over a 25-year period. The results show that while both marketing and R and D capitals have significant and direct positive associations with survival as a Fortune 500 firm, the moderating effects of industry growth on the relationships between marketing capital and survival as a Fortune 500 firm and between R and D capital and survival as a Fortune 500 firm is asymmetric. It is positive for marketing capital but negative for R and D capital. Thus, to retain firms‘ position on the Fortune 500 list, managers may want to consider investing more in marketing (R and D) when industry growth is high (low).
In the second essay, I examine the effect of advertising capital and R and D capital, their complementarities, and their interactions with the environmental contingency factors of dynamism, munificence, and complexity on sales growth, profit growth, and market value growth. Using dynamic panel data analysis of 185 firms over an eight year period (2000-2007), I uncover a nuanced understanding of how advertising and R and D capital affect these performance measures. My results show that both R and D capital and advertising capital directly affect sales growth, but neither has a direct impact on profit growth. Furthermore, R and D capital has a direct impact on market value growth. I also find that while the interaction of advertising capital and R and D capital does not directly affect sales growth or market value growth, it has a positive direct impact on profit growth. Finally, I find that environmental contingencies matter. For instance, environmental dynamism negatively (positively) moderates the relationship between R and D (advertising) capital and sales growth.
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Li, Flora. "Organic Thin Film Transistor Integration." Thesis, 2008. http://hdl.handle.net/10012/3745.
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This thesis examines strategies to exploit existing materials and techniques to advance organic thin film transistor (OTFT) technology in device performance, device manufacture, and device integration. To enhance device performance, optimization of plasma enhanced chemical vapor deposited (PECVD) gate dielectric thin film and investigation of interface engineering methodologies are explored. To advance device manufacture, OTFT fabrication strategies are developed to enable organic circuit integration. Progress in device integration is achieved through demonstration of OTFT integration into functional circuits for applications such as active-matrix displays and radio frequency identification (RFID) tags.
OTFT integration schemes featuring a tailored OTFT-compatible photolithography process and a hybrid photolithography-inkjet printing process are developed. They enable the fabrication of fully-patterned and fully-encapsulated OTFTs and circuits. Research on improving device performance of bottom-gate bottom-contact poly(3,3'''-dialkyl-quarter-thiophene) (PQT-12) OTFTs on PECVD silicon nitride (SiNx) gate dielectric leads to the following key conclusions: (a) increasing silicon content in SiNx gate dielectric leads to enhancement in field-effect mobility and on/off current ratio; (b) surface treatment of SiNx gate dielectric with a combination of O2 plasma and octyltrichlorosilane (OTS) self-assembled monolayer (SAM) delivers the best OTFT performance; (c) an optimal O2 plasma treatment duration exists for attaining highest field-effect mobility and is linked to a “turn-around” effect; and (d) surface treatment of the gold (Au) source/drain contacts by 1-octanethiol SAM limits mobility and should be omitted. There is a strong correlation between the electrical characteristics and the interfacial characteristics of OTFTs. In particular, the device mobility is influenced by the interplay of various interfacial mechanisms, including surface energy, surface roughness, and chemical composition. Finally, the collective knowledge from these investigations facilitates the integration of OTFTs into organic circuits, which is expected to contribute to the development of new generation of all-organic displays for communication devices and other pertinent applications. A major outcome of this work is that it provides an economical means for organic transistor and circuit integration, by enabling use of the well-established PECVD infrastructure, yet not compromising the performance of electronics.
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Feng, Ping-Chi, and 馮鈵棋. "Organic thin film solar cells." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/63381782999491543447.
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碩士國立臺灣海洋大學
光電科學研究所
98
Organic photovoltaic devices have gained a broad interest due to their potential for large-area low-cost solar cells. In this thesis, we used a series of novel p-type small organic molecules as the electron donor and fullerene derivatives (C60, PCBM) as the electron acceptor to form simple bulk heterojunction solar cells. Among them, LCC1 shows high hole mobility (h ca.10-4~ 10-5 cm2/Vs), good absorption coefficients, small molecular weight and favourable solution proceessability, which can be applied in thermal evaporation and solution process. Here, we successfully deposited photoactive layer by cosublimation of LCC1:C60 and by spin-coating mixtures of LCC1:PCBM. In thermal evaporation, LCC1:C60 in ratio of 3:1 has best performance. Short circuit current density is 2.74 mA/cm2, while the maximum efficiency could be 0.76 %. In solution process, LCC1:PCBM in ratio of 1:1 that has best performance. Short circuit current density is 3.21 mA/cm2, while the maximum efficiency could be 1.06 %.
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Liu, Miaoyin [Verfasser]. "Organic thin-film photovoltaics / Miaoyin Liu." 2010. http://d-nb.info/1004190492/34.
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Lu, Hsueh-Han, and 呂學漢. "Organic thin-film transistor with organic acceptors for ammonia gas sensor." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/3w2u75.
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碩士國立交通大學
光電工程研究所
103
In this thesis, we fabricated a p-type organic thin-film transistor (OTFT) with 2,7-dioctyl [1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) active layer and 2,3,5,6-tetrafluoro- 7,7,8,8-tetra-cyanoquinodimethane (F4-TCNQ) modification layer for ammonia (NH3) gas sensor. The modified OTFT did not only improve the carrier mobility and threshold voltage, but also enhanced the sensing ability at the low ammonia concentration environment (0.5 ppm). The device can be applied to monitor ammonia for the patients with liver disease. The sensing mechanism was discussed. The effect of surface modification under various relative humidity was also investigated.
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Li-ZhenYu and 游力蓁. "Investigation of bistable organic thin film transistors and organic memory devices." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/26503818225943833213.
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博士國立成功大學
微電子工程研究所碩博士班
98
The current?voltage characteristics of the gate?controlled three?terminal organic?based transistors with memory effect and negative differential resistances (NDR) were studied. Gold and 9,10-di(2-naphthyl)anthracene (ADN) were used as the metal electrode and active channel layer of the transistors, respectively. By using various gate?source voltages, the memory and NDR characteristics of the transistors can be modulated. The memory and NDR characteristics of the transistors were attributed to the formation of trapping sites in the interface between Au electrode and ADN active layer caused by the defects, when Au metal deposited on the ADN active layer. However, the different in the current values for the ON and OFF states can be improved. The vertical structure was used to improve the memory characteristics of the transistors. Three?terminal vertical organic memory transistors were fabricated to investigate the memory mechanisms and the relation between memory behavior and applied electrical field. The 9,10-di(2-naphthyl)anthracene (ADN) was used as the active channel layer for the organic memory transistors. In both the ON and OFF state of the organic memory transistors, the drain?source currents (IDS) were modulated by applying various gate?source voltages (VGS). The switching drain?source voltage (VDS) decreased with an increase in applied VGS voltages. The ON/OFF IDS current ratio of the organic memory transistors could be modulated up to the maximum value of 2.02x105 by applying VGS voltage bias. To investigate the memory bistable mechanisms of organic memory devices, the structure of [top Au anode/9,10-di(2-naphthyl)anthracene (ADN) active layer/bottom Au cathode] was deposited using a thermal deposition system. The Au atoms migrated into the ADN active layer was observed from the secondary ion mass spectrometry. The density of 9.6×1016 cm-3 and energy level of 0.553 eV of the induced trapping centers caused by the migrated Au atoms in the ADN active layer were calculated. The the memory bistable behaviors of the organic memory devices were attributed to the induced trapping centers. The energy diagram was established to verify the mechanisms.
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Wu, Jo-Pai, and 吳若白. "Organic-synthesized Polypeptides as Dielectric Materials for Organic Thin-Film Transistors." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/08073041732567648273.
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碩士國立清華大學
材料科學工程學系
102
Proteins such as silk fibroin, gelatin and bovine serum albumin were reported to be excellent gate dielectrics for pentacene OTFTs. The purpose of this research is to clarify the role of amino acids, which made up of protein. By the chemical method called “Ring-opening polymerization of N-carboxy anhydride” (NCA ROP), polypeptides were synthesized as gate dielectric materials for OTFTs. All the OTFTs exhibit transistor characteristics. In this study, we synthesize Serine and Alanine into homopolypeptides and random copolypeptides of different ratio. These peptides were spin-casted as dielectrics for pentacene thin film transistors. The results show that, hysteresis is influenced by changing the ratio of amino acids, and the electrical characteristics are altered by the temperature treatment on dielectric thin films. For the device that contains 20% Serine units under 80℃ treatment, a field effect mobility value of 0.87 cm2V-1s-1 and a threshold voltage of -0.67 V are achieved.
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chuan, Yu chih, and 游智全. "Process Investigation of Organic Thin Film Transistors." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/52536539662136785614.
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碩士長庚大學
光電工程研究所
92
Organic thin film transistors competitive for applications requiring fabricated on large area coverage and flexible electronic , such as commercial flexible poster、recognizing 、system、sensor、E- Paper. We report on the searches of organic thin film transistors fabrication in our thesis. we will excepted useful for developing of organic transistors. Our investigation has two key point mainly: (1)The paper hopes to use the high electric coefficient materials : Al 2O3 and HfO2 increase accumulated the electric charge to reduce the voltage of operating by meeting our request of having . At first of the experiment made organic transistors, three groups dielectric layer lie between characteristic curves of received and is tend to made at first by unanimous experiments . In the ID-VD figure, we suppose that it is an electrode and the organic materials is schottky contact relations, so we use the Au instead to regard as Source、Drain, the organic is P3HT To become Ohmic contact ,and reduce the length of road , and gain the IDVD and IDVG . Figure of organic transistor , ITS characteristic curve is similar to theory. (2)The paper hopes to build inkjet printing electrode .we hopes to manufacture in the low temperate conditions , and to make in the large-area . At first of the experiment made inkjet printing IJAG metal . The inkjet printing IJAG metal experiment to discover Coffee ring behavior. we are succeed improvement Coffee ring behavior and high resistance to use Hydrophilic and Hydrophobic relation .
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Lin, Yung-Sheng, and 林永昇. "High Efficiency Transparent Organic Thin Film Transistors." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/53959590162272131414.
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碩士國立交通大學
光電工程系所
94
One novel electrode-architecture has been adapted to fabricate transparent organic thin-film transistors (OTFTs). Due to the high injection barrier of the indium-tin-oxide (ITO)/pentacene interface, the device exhibited a non-ideal behavior. After the modification of the contact by inserting a thin-layer of one metal oxide (MoO2 or V2O5), the device performance was improved dramatically. By using the novel electrode architecture, an OTFT with more than 60 % transmittance in the visible region has been demonstrated. In addition, the transmittance was further improved by reducing the thickness of the semiconducting layer, which has been identified as the main component absorbing the visible light in the devices. Comparable device performance was still obtained, even though the thickness of pentacene was reduced to 200Å. As a result, one OTFT with over 70% transmittance has been demonstrated successfully. It is anticipated that the transparent OTFTs would be very suitable to be the driving circuits for liquid crystal displays (LCDs).
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Su, Wei-Chi, and 蘇威吉. "Design of Organic thin-film gas sensors." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/32179109779481572616.
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碩士國防大學理工學院
光電工程碩士班
97
The design of gas sensor with array organic thin films is discussed. Resistivity change of phenylene films from absorbing to-be-measured gas molecules can help distinguish the pernicious gases from others. This research is aimed at development of signal-acquiring circuit, control and identification software. We have finished designing the portable gas sensor, building the prototype, and creating the useful database to identify industrial pernicious gas such as ethyl alcohol ethanol, methyl ethyl ketene, trichloromethane, tetrahydrofuran and xylene. So far it can distinguish five gases described above real-time; besides, in the future it can also utilized to detect and analyze other pernicious gases through training.
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Yeh, Chia-Ming, and 葉佳明. "Synthesis of Soluble Organic Thin film transistors." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/40109234357727157180.
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碩士國立中央大學
化學研究所
99
Asymmetric fused thiophene compound (11) was synthesized by “one-pot” reaction. Based on compound (11), derivatives (1) and (2) have been developed. Both compounds exhibit p-type field-effect performances with mobility of 0.026 and 9x10-4 cm2/Vs via vacuum evaporation, respectively. Compounds (3) ~ (9) have been successfully developed based on bithiophene compound (18). Preparation of soluble compound (18) has been improved with better yield. Compounds (6), (7), and (8) exhibit good field-effect performances with high mobility of 0.15, 0.38, and 0.24 cm2/Vs via solution process, respectively. All of these new semiconductor materials exhibit good stability under light, air, and thermal conditions.
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Huang, Yu-Jen, and 黃昱仁. "Air-stable Ambipolar Organic Thin-Film Transistors." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/99446356586263355691.
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碩士國立交通大學
顯示科技研究所
96
Air-stable ambipolar organic thin-film transistors (OTFT) based on the double active layer of pentacene / PTCDI-C8 have been made. Because the n-channel performance is easily affected by water and oxygen, the device on SiO2 can only exhibited ambipolar OTFT properties in inert conditions. However, after modification of the surface of the SiO2 by polymers, the device exhibited ambipolar characteristics under ambient conditions. The ambipolar OTFT still work after 40 days in the air. According to the experiments, we infer that hydroxyl groups on dielectric have a profound effect on n-channel properties. Furthermore, from the capacitance-voltage measurements, we observed that ambipolar OTFT accumulated holes and electrons under negative and positive voltages respectively. Finally, a CMOS-like inverter has been constructed by using two identical ambipolar transistors. The inverter could operate in both the first and third quadrants, thereby simplifing the IC design.
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Chuang, Yen-yu, and 莊儼郁. "Room-Temperature Processed Organic Thin Film Transistors." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/75228396293886924094.
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碩士國立臺灣大學
光電工程學研究所
90
OTFTs based on conjugated polymer, oligomers, or fused aromatics have been envisioned as a viable alternative to the traditional thin-film transistors (TFTs) based on inorganic materials. The unique processing characteristics and demonstrated performance of OTFTs suggest that they may be competitive candidates for existing or novel TFT applications requiring large area coverage, structural flexibility, low temperature processing, and low cost. In this thesis, room-temperature processed pentacene organic thin film transistors have been successfully fabricated on n+-Si/SiO2 substrates and characterized. Various device structures have been examined to reduce gate current and to make output characteristics normal. The characteristics of OTFTs do scale with the channel dimensions, as expected from the conventional MISFET current formulation. Pentacene films with smaller thickness are less crystallized, therefore result in lower mobility but also lower subthreshold slope of OTFTs. Subthreshold slope 7.65 V/decade is reached for OTFTs with additional detergent/DI water treatment of the oxide surface, and saturation-region mobility 0.49 cm2/V•sec is achieved for OTFTs with additional detergent/DI water/UV-Ozone treatment of the oxide surface.
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Tsai, Li-Shiuan, and 蔡立軒. "Nitrogen incorporated Hafnium Dioxide dielectric thin film For Organic Thin Film Transistors." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/05427454364168925544.
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碩士國立清華大學
材料科學工程學系
97
Hafnium oxide is a high-k dielectric material which have dielectric constant of 25,high-k dielectric material use to be a gate oxide can decrease the threshold voltage and device scale for low voltage and microelectronics. Organic thin film transistors has been used to fabricate soft electronics devices. The active layers for OTFTs is numerous, pentacene for our research is one of most used OTFTs active layers. In this thesis, we fabricate the HfO2 and HfON thin film by RF Reactive Magnetron Sputter System. The target is Hf metal for 99.99%, and we use Mass Flow Controller to put the Ar-O2-N2 mix gas in the chamber.HfO2 or HfON thin film would deposit on the substrate by Hf sputtering atoms react for O2 and N2.We deposit different recipes film to research their properties. Before depositing the dielectric film, we pre-deposit a Hf thin film. The thin film can decrease roughness for dielectric film, surface roughness decrease from Ra=1.972nm without Hf pre-sputtered to Ra=1.414nm with Hf pre-sputtered, this fabrication increase the device characteristics ,mobility increase from 0.086 cm2/V．s to 0.174 cm2/V．s, threshold voltage decrease from -0.7V to -0.31V,on-off ratio increase from 0.9x103 to 3.2x103, subthreshold swing decrease from -0.368 V/dec to -0.209 V/dec. In our research, a low surface energy dielectric film would have better device characteristics of pentacene based OTFTs. In this thesis, we deposit HfON thin film by Reactive Magnetron Sputter System, and make a OTFT device which have a better characteristics.
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Tsai, Hsing-Wang, and 蔡興旺. "Integration of Organic Solar Cells and Low Voltage Organic Thin Film Transistors." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/74829067654877324654.
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博士國立中央大學
電機工程研究所
99
Solar cells based on polymer materials have attracted a great deal of attention due to their low cost and potential for large-scale fabrication, through solution processes at low temperature. For commercial applications, the efficiency of polymer solar cells (PSC) must exceed 10%. But currently, most PSC devices remain far from that level of efficiency. For this reason, a number of researchers have focused on improving the electrical and physical characteristics of such devices through the development of new materials and the structural optimization. To meet the market demand for portable products, functional circuitry must be designed for low power consumption operating on self-contained power supplies. With this in mind, designing a conductor-insulator-semiconductor (CIS) structure that combines polymer solar cells (PSC) with polymer thin film transistors (TFTs) working at low voltage is the primary objective behind this thesis. The advantages of such integration would be the simplification of circuitry and the simplification of the fabrication process. Propress made in this study show possibility for the development of thin, lightweight products in the future. In chapter 2, we study a conductor/insulator/conductor (CIC) multi-layer electrode as a replacement for those traditional ones used in PSCs. The work function of this multi-layer electrode was improved by the dipole effect on the surface of the electrode, thereby influencing the internal electric field, and to enhancing the efficiency of the solar cells. In chapter 3, the thickness of the insulator in the structure of the CIS can be controlled through thermal treatment after spin-coated onto the organic electrode. With this controlled technique, the efficiency and the lifespan of the PSC is enhanced. In chapter 4, a low voltage polymer TFT is fabricated with a CIS structure using a poly(3-hexylthiophene) (P3HT) semiconductor, and us electrical characteristic are discussed. The P3HT semiconductor is difficult to apply as a polymer TFT due to low conductivity. Enhancing the conductivity of polymer OTFTs by annealing is well known, but difficult to apply on a plastic substrate, due to low heat tolerance. For this reason, we propose a bias annealing technique with the advantages of rapid heating and highly localized heat radiation. A high input current can be obtained using polymer TFTs by bias annealing of the active layer, the principle of which is discussed later. In chapter 5, we focus on integrating the PSC and polymer TFTs on the same substrate, through the use of the CIS structural concept mentioned previously. This integrated device is given both the characteristic of PSC and polymer TFTs by forming the active layer through drop coating. In chapter 6, the experiment results mentioned previously are concluded, with suggestions for improving the integration of the structure in future studies.
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Huang, Sheng-Chieh, and 黃聖傑. "Investigation the organo-silicon barrier film deposited by magnetron PECVD." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/44668432124577593881.
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碩士國立中央大學
光電科學與工程學系
102
With the rapid development of technology, consumer electronics products gradually become an indispensable part of people's lives. However, electronics based on the silicon substrate, glass fiber and glass substrates has been difficult to achieve light, thin and low-cost development goals, so the use of thin, flexible, low-cost flexible plastic substrate becomes an ideal develop targets for manufactures. Although the plastic substrate has the advantages such as light-weight, impact-resistant and rapid mass production, but its poor water vapor permeation barrier ability limit its application, therefore promote water vapor barrier film becomes a popular research topics. Silicon oxide film has good transparency and mechanical properties makes it a popular water vapor barrier material, but generally PECVD silicon oxide film coating process such as capacitive coupled PECVD operates at low vacuum environment (10-1 Torr), makes it difficult to match magnetron sputtering process under high vacuum enviroment (10-3 Torr) for continuous operation. Magnetron PECVD using magnetron sputtering gun as PECVD plasma source which makes PECVD process can operate in high vacuum environment (10-3 Torr), however silicon oxide coating by this method may leads to a large number of hydrocarbon content in layer, since the short residence time of monomer in plasma result to a lower degree of monomer fragmentation, thus reduce the effectiveness of the permeation barrier ability of silicon oxide film. In this research, silicon oxide water vapor barrier film on PET substrate deposited by magnetron PECVD in high vacuum environment (10-3 Torr). Although the side effect such as hydrocarbon content and high process temperature by magnetron sputter gun may deteriorate the barrier performance of the silicon oxide film, the improvement of vacuum degree may able to improve the compactness thus lower the WVTR value. Excess oxygen flow can further increase the Si(-O)4 content, but the etching effect by oxygen plasma on PET substrate may destroy the surface flatness then increase possibility of nano-crack by release of internal stress. 100W RF power, 10sccm O2, 0.25g/h HMDSO were applied to deposit a 50-nm-thick film with low WVTR and high transmittance above 90%. WVTR of the film reached the value of 0.139 g/m2/day lower than the best WVTR value, 0.3 g/m2/day, of films deposited by HMDSO using PEVCD process with other plasma source.
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Kuo, Chung-Chen. "High performance small-molecule organic thin film transistors." 2005. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1108/index.html.
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Park, Sung Kyu. "High mobility solution processed organic thin film transistors." 2007. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2145/index.html.
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Cobb, Brian Hardy 1982. "Dynamic response of polycrystalline organic thin film transistors." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-794.
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In this dissertation, charge transport through organic field effect transistors is explored. In particular, small molecule-based devices consisting of Pentacene semiconducting thin films are investigated. The relationship between electric field and carrier velocity is explored over a wide range of electric fields. These velocities are then compared to directly measured velocities measured from transient measurements.
New device structures are fabricated in order to provide low voltage operation, along with a method to stabilize the output response and reduce bias stress effects. A novel method is proposed to investigate the dynamics of trap response rate in highly localized systems through the characterization of the large signal frequency response of a
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device. This method is then used to gain greater insight into bias stress effects and the ability of a transistor to respond to a rapidly changing input.
A greater understanding of the transport of charge through a channel is obtained, leading to a more realistic picture in which a single mobility value is an insufficient description of carrier transport through a material.text