Download or read book Enhanced Charge Transport in Polymer Thin film Transistors Through Structural and Morphological Optimization written by Brandon Smith and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic semiconductors offer the potential for low cost, large area, and flexible electronic devices. However, the lower performance of organic materials relative to silicon, germanium, and other inorganic components has prevented widespread implementation. Correspondingly, the overarching goals of the work outlined in this dissertation focus on exploring the fundamental properties and intermolecular interactions of conjugated polymers and utilizing the findings to develop routes for improving thin-film transistor performance. Charge transport in organic active layers depends largely on the intrinsic carrier mobility of the semiconductor, the morphology achieved during processing and fabrication, as well as the effectiveness of the post-processing techniques. In this work, we investigate the influence of each and will show how appropriately tuning polymorphism, copolymerization between strong and weakly crystallizing moieties, and fluorine substitution on delocalized cores significantly enhance transistor characteristics. Crystalline organic molecules often exhibit the ability to assemble into multiple crystal structures depending on the processing conditions. Exploiting this polymorphism to optimize molecular orbital overlap between adjacent molecules in the unit lattice is a viable method for improving charge transport within the material. We have employed grazing-incident X-ray diffraction to demonstrate the formation of tighter stacking poly(3-hexylthiophene-2,5-diyl) polymorphs in films spin coated from ferrocene-containing solutions. As a result, the addition of ferrocene to casting solutions yields thin-film transistors which exhibit approximately three times higher source-drain currents and charge mobilities than neat polymer devices. Nevertheless, thorough analysis of the active layer reveals that all ferrocene is removed during the spin coating process, which may be an essential factor to achieve good mobilities. Such insights gleaned from ferrocene/poly(3-hexylthiophene) mixtures can serve as a template for selection and optimization of other small molecule/polymer systems with greater baseline charge mobilities. Block copolymerization provides yet another avenue for altering the crystal packing behavior and morphology of polymer semiconductors. Our work reveals that covalently coupling a weakly crystalline acceptor polymer with excellent electron mobility to a strongly crystallizing donor unit can induce ordering in the less crystalline block. Grazing-incidence X-ray scattering results confirm that shorter interchain spacing distances are obtained in poly(3-hexylthiophene)-b-poly(fluorene-dithiophene-benzothiadiazole) copolymers compared with neat poly(fluorene-dithiophene-benzothiadiazole) films. An enhancement in the ordering of the acceptor moiety was also observed both in neat homopolymer and copolymer samples after thermal annealing at 195 C. Consequently, the electron mobility of the block copolymer, measured in thin-film transistors with aluminum contacts, surpassed that of either homopolymer and peaked at annealing temperatures between 195 210 C. Several recent reports have surfaced in the literature in which fluorinated analogues of various donor/acceptor copolymers consistently surpass their non-fluorinated counterparts in terms of performance. Prior studies have speculated as to the origin of this fluorine effect, but concrete evidence has not been forthcoming. Using a benzodithiophene and benzotriazole copolymer series consisting of fluorinated, partially-fluorinated, and non-fluorinated analogues, we confirm that the addition of fluorine substituents beneficially impacts charge transport in polymer semiconductors. Transistor measurements demonstrated a 5x rise in carrier mobilities with the degree of fluorination of the backbone. Furthermore, X-ray diffraction data indicates progressively closer packing between the conjugated cores and an overall greater amount of crystallinity in the fluorinated materials. It is likely that attractive interactions between the electron-rich donor and fluorinated electron-deficient acceptor units induce very tightly stacking crystallites, which reduce the energetic barrier for charge hopping. In addition, a change in crystallite orientation was observed from primarily edge-on without fluorine substituents to mostly face-on with dual fluorine groups. We also introduce a promising post-processing technique adapted from existing zone purification and recrystallization methods. Zone annealing and zone refining are proposed for imparting directionality to the crystallization process, thereby increasing the size of crystallites and uninterrupted conjugation lengths within polymer films. A custom nichrome wire-based zone heating apparatus developed for zone refining thin films is described, and preliminary results with poly(3-hexylthiophene) are presented. A comparison with the UV-Vis absorbance of films annealed statically on a hot plate suggests that similar conjugation lengths can be achieved in approximately a sixth of the time with zone refining. Further optimization and investigatory studies are required before the procedure can be successfully extended to transistor samples, but zone crystallization appears to be a highly compatible post-processing approach for large scale manufacturing. The final portion of this work was dedicated to the development of potential integration venues for organic devices. Applications which take full advantage of the unique properties of polymer semiconductors will be needed as organic electronics begin the arduous transition into the commercial sphere. As such, neutron and X-ray detection systems represent two categories where very large area and flexibility would be invaluable. We therefore explore the feasibility of sensitizing conjugated materials towards either neutrons or X-rays through the incorporation of elements possessing excellent neutron capture or X-ray absorption properties. The projected mechanisms and challenges associated with direct radiation detection are discussed, and the results obtained from numerous screening experiments, conducted to determine which compounds maintain acceptable performance in transistors, are included. Based on these trials, boron nitride, 10B-enriched boric acid, and ruthenocene blended with poly(3-hexylthiophene) at extraordinarily high loadings were identified for further scrutiny and eventual response testing with an X-ray or neutron source. In summary, the objectives set forth for this work have been successfully realized. We examined the impact of several parameters governing charge transport in organic semiconductors, and based on our conclusions, we have identified three approaches for substantially augmenting the performance of polymer field-effect transistors. We have also considered a useful post-process treatment for large scale device fabrication and illustrated the benefits and potential for adapting conjugated materials for novel detection applications. The contributions of the research efforts expounded within this dissertation have far reaching implications yet represent only a small part of the general advance of the organic semiconductor field. Significant progress is being made on many critical fronts, and provided the allure of light weight, completely conformable electronics remains strong, we expect to continue witnessing the steady emergence of ever more numerous devices and gadgets based on organic transistors and diodes.

Download or read book Microstructural Control of Charge Transport in Organic Blend Thin Film Transistors written by and published by . This book was released on 2014 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, the charge-transport processes in organic p-channel transistors based on the small-molecule 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene (diF-TES ADT), the polymer poly(triarylamine)(PTAA) and blends thereof are investigated. In the case of blend films, lateral conductive atomic force microscopy in combination with energy filtered transmission electron microscopy are used to study the evolution of charge transport as a function of blends composition, allowing direct correlation of the film's elemental composition and morphology with hole transport. Low-temperature transport measurements reveal that optimized blend devices exhibit lower temperature dependence of hole mobility than pristine PTAA devices while also providing a narrower bandgap trap distribution than pristine diF-TES ADT devices. These combined effects increase the mean hole mobility in optimized blends to 2.4 cm(2)/Vs - double the value measured for best diF-TES ADT-only devices. The bandgap trap distribution in transistors based on different diF-TES ADT:PTAA blend ratios are compared and the act of blending these semiconductors is seen to reduce the trap distribution width yet increase the average trap energy compared to pristine diF-TES ADT-based devices. In conclusion, our measurements suggest that an average trap energy of

Download or read book Synthesis and Performance Characterization of Polymer Semiconductors for Organic Thin Film Transistors written by Chang Guo and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As the most promising semiconductor candidates for organic thin film transistors (OTFTs), donor-acceptor (D-A) type [pi]-conjugated polymers have received much attention in the recent years. Their excellent printability, light weight, mechanical robustness and flexibility are desirable characteristics for low cost and portable electronics. Some issues of polymer semiconductors as such relatively low charge carrier mobility compared to that of silicon as well as the poor stability during manufacturing and device operation in an ambient environment still remain. Although extensive efforts have been made to develop electron acceptor building blocks, which are considered to be critical for achieving high mobility, very few electron acceptors for constructing novel high performance D-A polymers are available. Nowadays most D-A polymers were synthesized using traditional Suzuki or Stille coupling, which use boron- or tin-containing monomers that require extra synthetic steps and are highly toxic in some cases (such as organotin monomers). As an alternative method, the direct (hetero)arylation polymerization (DHAP), provides a new approach to constructing D-A polymers in a cost-effective and environment friendly manner. Certain polymers synthesized by DHAP have demonstrated similar or even better performance compared to the polymers made by other methods. However side reactions and limitations on the types of monomers for DHAP have been reported. To bring the OTFT performance of polymer semiconductors to the next level, new acceptor building blocks and a further study of DHAP need to be exploded. In the first part of this thesis (Chapters 2-4), a novel electron acceptor building block, indigo is chosen, considering its electron deficiency property, highly coplanar geometry and ease of synthesis. Furthermore, indigo and its small molecule derivatives have been demonstrated to be promising semiconductors in OTFTs. However, indigo-containing polymer semiconductors have not been reported yet. In this study, we used 6,6'-indigo as an electron acceptor to successfully develop several n-type electron transport semiconductors. Surprisingly, when 5,5'-indigo was used, the opposite p-type hole transport performance was observed. To the best of our knowledge, this is the first observation that the charge transport polarity could be controlled or switched through different regiochemical connections of a building block. The second part of this thesis (Chapters 5 and 6) focuses on the optimization and development of dipyrrolopyrrole (DPP) based polymers. In Chapter 5, DHAP is used to construct a novel high performance pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (1,4-DPP)-thiazole based polymer. Two synthetic routes are compared and discussed, and the polymer synthesized under optimized DHAP conditions showed better performance than that of a similar polymer obtained by Stille coupling. In Chapter 6, pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (1,3-DPP), an isomer of 1,4-DPP, is developed for constructing polymer semiconductors with promising performance in OTFTs. Systematic studies on the synthesis of these new acceptor building blocks as well as the exploration of DHAP have provided insights into the structure-property relationships of novel D-A polymers and may lead to the discovery of the next generation high mobility polymer semiconductors.

Download or read book Semiconducting Polymer Composites written by Xiaoniu Yang and published by John Wiley & Sons. This book was released on 2012-10-05 with total page 553 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part of Semiconducting Polymer Composites describes the principles and concepts of semiconducting polymer composites in general, addressing electrical conductivity, energy alignment at interfaces, morphology, energy transfer, percolation theory and processing techniques. In later chapters, different types of polymer composites are discussed: mixtures of semiconducting and insulating or semiconducting and semiconducting components, respectively. These composites are suitable for a variety of applications that are presented in detail, including transistors and solar cells, sensors and detectors, diodes and lasers as well as anti-corrosive and anti-static surface coatings.

Download or read book Examining and Controlling the Morphology of the Photoactive Layer of Organic Photovoltaic Devices written by Sameer Vajjala Kesava and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electronic devices such as solar cells, transistors and light-emitting diodes (LEDs) fabricated using organic semiconductors offer a potential feasible alternative to their inorganic counterparts due to several advantages such as ease of processing (ink-jet printing, roll-to-roll processing), flexibility and excellent control over the electronic properties through chemical modifications. Compared to the inorganic semiconductors, however, the performance of organic semiconductor-based electronic devices are much lower. For example, in the case of photovoltaic devices (solar cells), the power-conversion efficiencies are still lower (7%-10%) compared to that of inorganic solar cells (> 25%). The efficiency of a solar cell is determined, among other factors, to a significant extent by the morphology of the active layer, the thin film where photons are absorbed and charges generated. Even though significant improvement in the efficiencies have been achieved, mainly through band-gap engineering and processing optimization, a fundamental understanding of the structural and morphological effects of the active layer on the performance of organic photovoltaic devices remains obscured. In this work, the focus is on examining the structure-function relationships in solution-processed bulk-heterojunction organic photovoltaic devices and development of processing techniques for device optimization. A bulk-heterojunction device is formed by mixing of donor-acceptor semiconductors, and the subsequent structure formed in the active layer is dictated by the miscibility and crystallization of the components, which are functions of processing conditions. Excitons (electron-hole pairs bound by coulombic forces) formed in the donor semiconductor upon absorption of light have a diffusion length of around 5-10 nm before recombination occurs. Thus the structural length scales formed in the active layer determine the number of excitons that can dissociate into charges. We have examined the microstructure of poly(3-hexyl thiophene) (P3HT) donor and phenyl-C61-butyric acid methyl ester (PC61BM) acceptor mixture using grazing incidence small angle X-ray scattering (GISAXS) and energy-filtered transmission electron microscopy (EFTEM) to characterize the in-plane structural length scales for various processing conditions such as annealing temperatures and spin-casting solvents. Our results show that the structural length scales are driven by self-limiting P3HT crystallization upon thermal annealing, which correlate to the internal quantum efficiencies of the devices. In contrast, it has been reported in the case of poly[2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT)/ fullerene mixtures that thermal annealing results in crystallization of PBTTT with unconstrained lateral dimensions causing coarsening of the in-plane characteristic length scales. Thus the morphological evolution in polymer/fullerene solar cells, and consequently device performance, depends on the crystallization motif of the polymer. The microstructure resulting from mixing of donor-acceptor semiconductors can yield distinctive donor-acceptor interfaces that affect charge separation and recombination. Our studies utilizing a low band-gap poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]germole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl] (PGeBTBT) donor and PC71BM acceptor examine the effects of mixing on the charge generation in a device. Composition of mixed phases ascertained qualitatively and quantitatively using EFTEM and resonance soft X-ray scattering (RSOXS) show that the concentration of polymer in the mixed phase decreases as fullerene concentration in the mixture is increased. This resulted in a concomitant increase in the device performance. Similarly, photo-induced absorption studies carried out using ultrafast spectroscopy show increase in polaron concentration with increase in purity of the mixed phase. Grazing-incidence wide-angle X-ray scattering (GIWAXS) data show a change in fullerene aggregation with increase in fullerene concentration in the mixture. This indicates that adding polymer to the mixed phase results in dispersal of fullerene, and consequently, changing the local environment of the polymer affects formation of charge-transfer states and subsequent dissociation into individual charges. Thus, high interfacial area that is formed upon intimate mixing of polymer/fullerene, considered ideal for efficient exciton dissociation, counteracts through high charge recombination. Our results show that the composition of mixed phases affects charge separation at the interface consequently affecting device performance of organic photovoltaics. Another important aspect that has been shown to affect device performance of organic photovoltaics is the orientation of polymer crystals with respect to the substrate. For example, P3HT predominantly orients in an edge-on configuration, i.e., with the [pi]-[pi] bond stacking direction parallel to the substrate. It is hypothesized that out of plane [pi]-[pi] stacking, called face-on orientation, is important for effective charge transport. One way to achieve enhancement of face-on orientation is by directional crystallization which has been shown to be very effective for P3HT -- in this case, directional crystallization from solution. In this context, 'zone-annealing' is relevant as it has been employed to directionally crystallize polymers. In this work, we designed and developed the zone-annealing equipment, which can yield thermal gradients greater than 60°C/mm. Preliminary results from GIWAXS experiments on P3HT/PC61BM thin films show anisotropy in the structure and a moderate enhancement of face-on orientated P3HT crystallites. This technique was extended to organic field-effect transistors (OFET) to enhance charge mobilities through directional crystallization of organic semiconductors. In case of P3HT, the increment in charge mobilities was by a factor of 2 upon zone-annealing. However, in the case of organic small molecule semiconductor, 2,7-dioctyl[1]benzo- thieno[3,2-b][1] benzothiophene (C8-BTBT) , highly aligned crystalline domains were obtained -- a very promising result for fabricating high mobility OFETs. Thus, the zone-annealing technique provides a handle for controlling the morphology of organic thin film electronic devices.

Download or read book Microstructure and Charge Transport in Conjugated Polymers written by Chenchen Wang and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Conjugated polymers have attracted broad interest in the past few decades due to their potential applications in organic light emitting diodes, low-cost flexible circuits, biosensors and photovoltaics. Because of their semicrystalline nature, the spatial arrangement of the crystallites and the disordered regions would have strong impact on the charge transport properties of conjugated polymer thin films. Therefore, in this presentation, I will focus on understanding the relationship between the film's morphology, microstructure and electronic properties, and how to fabricate desired structure to achieve devices with novel electronic performance. In the first part of the presentation, I will show that the device's electronic performance can be greatly improved by engineering its structure in solution based fabrication process. The binary blends of regioregular (rr) and regiorandom (RRa) P3HT are used to form desired FET structures. X-ray diffraction of the blended films is consistent with a vertically-separated structure, with rr-P3HT preferentially crystallizing at the semiconductor/dielectric interface. Because of the ultra-thin rr-P3HT active layer at the interface, these devices not only preserve high mobility in rr-P3HT, but also eliminate the short channel effects due to bulk currents, suggesting a new route to fabricate high performance, short-channel and reliable organic electronic devices. After that, I will discuss the microstructural origin of high mobility in poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophenes) (PBTTT) thin-film transistors (TFTs). Charge transport in PBTTT TFTs is analyzed with a mobility edge (ME) model and compared to these in poly(3-hexylthiophene) (P3HT) TFTs. With TEM characterization of delaminated films, we conclude that the improved performance of PBTTT compared to P3HT is not due to a low trap density but rather to a high mobility in the crystallites. Finally, the third part of the presentation will focus on optical characterization of doping in conjugated polymers. UV-vis and IR absorption spectra of 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) doped P3HT at different doping concentration are measured and analyzed. Absorption peaks from P3HT, F4TCNQ, F4TCNQ anion and P3HT polaron/bipolarons are identified and decomposed. The P3HT polaron/bipolarons cross sections in UV-vis region are estimated, which can be used to evaluate doping efficiency in this material.

Download or read book Introduction to Organic Electronic and Optoelectronic Materials and Devices written by Sam-Shajing Sun and published by CRC Press. This book was released on 2016-10-03 with total page 1069 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the combined subjects of organic electronic and optoelectronic materials/devices. It is designed for classroom instruction at the senior college level. Highlighting emerging organic and polymeric optoelectronic materials and devices, it presents the fundamentals, principle mechanisms, representative examples, and key data.

Download or read book Polymer Thin Films written by Ophelia Kwan Chui Tsui and published by World Scientific. This book was released on 2008 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ch. 1. Block copolymer thin films / J.-Y. Wang, S. Park and T. P. Russell -- ch. 2. Equilibration of block copolymer films on chemically patterned surfaces / G. S. W. Craig, H. Kang and P. F. Nealey -- ch. 3. Structure formation and evolution in confined cylinder-forming block copolymers / G. J. A. Sevink and J. G. E. M. Fraaije -- ch. 4. Block copolymer lithography for magnetic device fabrication / J. Y. Cheng and C. A. Ross -- ch. 5. Hierarchical structuring of polymer nanoparticles by self-organization / M. Shimomura ... [et al.] -- ch. 6. Wrinkling polymers for surface structure control and functionality / E. P. Chan and A. J. Crosby -- ch. 7. Crystallization in polymer thin films: morphology and growth / R. M. Van Horn and S. Z. D. Cheng -- ch. 8. Friction at soft polymer surface / M. K. Chaudhury, K. Vorvolakos and D. Malotky -- ch. 9. Relationship between molecular architecture, large-strain mechanical response and adhesive performance of model, block copolymer-based pressure sensitive adhesives / C. Creton and K. R. Shull -- ch. 10. Stability and dewetting of thin liquid films / K. Jacobs, R. Seemann and S. Herminghaus -- ch. 11. Anomalous dynamics of polymer Films / O. K. C. Tsui.

Download or read book Solution Processable Organic Semiconducting Materials for Thin Film Transistors and Photovoltaic Applications written by Sang-wŏn Ko and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic transistors and solar cells offer the potential advantages of low-cost, large-scale fabrication by solution processing techniques, and compatibility with both flexible and lightweight plastic substrates. Continuous development of new organic materials has improved their performance, thus enabling the commercialization of these conducting polymers in recent years. However, understanding the relationship between polymer packing structures and mobilities is still lacking. Furthermore, to enable a polymer to serve as an effective donor material in bulk heterojunction (BHJ) solar cells, several important properties have to be considered, such as band gap, absorption coefficient, effective charge transport, and a relatively deep HOMO. Needless to say, careful balancing of these properties remains challenging. Thus, this thesis aims to gain a better understanding of materials design rules to address the above issues using two types of conjugated polymers. First, new donor-acceptor copolymers were designed and synthesized to gain insights into designing efficient donor materials in BHJ solar cells. Second, poly(3,4-disubstituted thiophene) derivatives were designed and synthesized to study relationships between structural design, packing, charge transport property, and solar cell performance. In the first part of my thesis, I have prepared vinylene linked co-polymers in order to achieve low bandgap polymers by extending [Pi]-conjugation lengths. I found that the hole mobilities of the polymers scaled with the molecular weights in these amorphous polymers. Optical absorption at longer wavelengths was improved by eliminating torsions along the polymer backbones. Current density (Jsc) in BHJ solar cells depended on the overall intensity of absorption and hole mobility of donor materials. Comparing to the amorphous vinylene linked co-polymers, charge carrier mobility could be enhanced by employing thienopyrazine based co-polymers, which contain rigid fused aromatic rings promoting well ordered inter-chain packing. Removing of the adjacent thiophene groups around the thienopyrazine acceptor core markedly increased the optical absorption of the polymer and raised its ionization potential, resulting in power conversion efficiency (PCE) of 1.57%. This investigation on the new co-polymers could provide a useful guideline for designing efficient donors for BHJ solar cells. In the second part of my thesis, I designed and synthesized polythiophene derivatives to understand structure-property relationships in detail. Despite their slightly larger band gaps, polythiophene derivatives are nonetheless important active materials due to their high absorption coefficients and high charge transport mobilities. Furthermore, their facile synthesis and ease of structural modifications with various substituents are the advantages of using polythiophene derivatives as model conjugated polymer systems. To examine the influence of backbone twisting on performance of transistors and BHJ solar cells, I systematically imposed twists within the conjugated backbones of poly(3,4-disubtituted thiophene (P34AT) using a unsubstituted thiophene spacer of varying sizes. When a moderate twist was introduced to the P34AT backbone, a 19% enhancement in the open-circuit voltage vs. poly(3-hexylthiopene) based devices and high PCE (4.2%) were achieved without sacrificing the short-circuit current density and the fill factor. Despite the high charge transport mobility (0.17 cm2/Vs), P34AT hardly showed [Pi]-[Pi] stacking in X-ray diffraction, suggesting that a strong [Pi]-[Pi] stacking is not always necessary for high charge carrier mobility; in which other potential polymer packing motifs (in addition to the edge-on structure) can lead to a high device performance. To gain further knowledge in structure-property relationships of the less explored 3,4-disubstituted polythiophene system, various P34AT derivatives were prepared and their opto-electronic property, packing structure, and device performance were studied. Among P34AT derivatives containing fused thiophene rings, a higher PCE was achieved with a benzodithiophene based polymer (PDHBDT) having a larger absorption coefficient, higher hole mobility, and deeper HOMO. The PDHBDT also exhibited a thermotropic phase transition behavior, leading to mobility up to 0.46 cm2/Vs where the polymer backbones adapt an edge-on lamellar packing structure. In the last part of this thesis, low band gap P34AT derivatives, which incorporate electron withdrawing groups, were prepared to improve photocurrent. However, I observed that a low absorption coefficient and a low hole mobility limited current density in solar cells. Thus, this indicates that low band gap polymers with strong absorption properties and good charge transports are critical towards molecular design for achieving high PCE. Collectively, through rational design and characterization of these novel polymers, this thesis has illustrated that better understanding of molecular design rules for engineering opto-electronic properties and packing behavior, will lead to higher device performance.

Download or read book Understanding Microstructure and Charge Transport in Semicrystalline Polythiophenes written by Leslie Hendrix Jimison and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconducting polymers are a promising class of organic electronic materials, with the potential to have a large impact in the field of macroelectronics. In this thesis, we focus on understanding the relationship between microstructure and charge transport in semicrystalline polythiophenes. A method is presented for the measurement of complete pole figures of polymer thin films using an area detector, allowing for the first time quantitative characterization of crystalline texture and degree of crystallinity. Thin film transistors are used to measure electrical characteristics, and charge transport behavior is modeled according to the Mobility Edge (ME) model. These characterization methods are first used to investigate the effect of substrate surface treatment and thermal annealing on the microstructure of polythiophene thin films, and the effect of microstructural details on charge transport. Next, we investigate the semicrystalline microstructure in confined polythiophene films. Pole figures are used to quantify a decrease in the degree of crystallinity of films with decreasing thickness, accompanied by an improvement in crystalline texture. Next, we investigate the influence of the degree of regioregularity, molecular weight and the processing solvent on microstructure (degree of crystallinity and texture) and charge transport in high mobility P3HT thin films. Surprisingly, when processing conditions are optimized, even a polymer with moderate regioregularity can form a highly textured film with high charge carrier mobility. Finally, we use films of P3HT with engineered, anisotropic in-plane microstructure to understand the importance and mechanism of transport across grain boundaries in these semicrystalline films. Results from this study provide the first experimental evidence for the application of a percolation model for charge transport in high molecular weight semicrystalline polymer semiconductors. Understanding how characteristics of the polymer as well as details of the processing conditions can affect the film microstructure and device performance is important for future materials design and device fabrication.

Download or read book Large Area and Flexible Electronics written by Mario Caironi and published by John Wiley & Sons. This book was released on 2015-01-13 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: From materials to applications, this ready reference covers the entire value chain from fundamentals via processing right up to devices, presenting different approaches to large-area electronics, thus enabling readers to compare materials, properties and performance. Divided into two parts, the first focuses on the materials used for the electronic functionality, covering organic and inorganic semiconductors, including vacuum and solution-processed metal-oxide semiconductors, nanomembranes and nanocrystals, as well as conductors and insulators. The second part reviews the devices and applications of large-area electronics, including flexible and ultra-high-resolution displays, light-emitting transistors, organic and inorganic photovoltaics, large-area imagers and sensors, non-volatile memories and radio-frequency identification tags. With its academic and industrial viewpoints, this volume provides in-depth knowledge for experienced researchers while also serving as a first-stop resource for those entering the field.

Download or read book Transparent Electronics written by Elvira Fortunato and published by . This book was released on with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book PEDOT written by Andreas Elschner and published by CRC Press. This book was released on 2010-11-02 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: While there is information available in handbooks on polythiophene chemistry and physics, until now, few if any books have focused exclusively on the most forwardly developed electrically conductive polymer, Poly (3,4-ethylenedioxythiophene)-otherwise known as PEDOT. This resource provides full chemical, physical, and technical information about this important conducting polymer, discussing basic knowledge and exploring its technical applications. Presented information is based on information generated at universities and through academic research, as well as by industrial scientists, providing a complete picture of the experimental and the practical aspects of this important polymer.

Download or read book Organic Photovoltaics written by and published by . This book was released on 2006 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thin Film Solar Cells written by Jef Poortmans and published by John Wiley & Sons. This book was released on 2006-10-16 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin-film solar cells are either emerging or about to emerge from the research laboratory to become commercially available devices finding practical various applications. Currently no textbook outlining the basic theoretical background, methods of fabrication and applications currently exist. Thus, this book aims to present for the first time an in-depth overview of this topic covering a broad range of thin-film solar cell technologies including both organic and inorganic materials, presented in a systematic fashion, by the scientific leaders in the respective domains. It covers a broad range of related topics, from physical principles to design, fabrication, characterization, and applications of novel photovoltaic devices.

Download or read book Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications written by Srabanti Ghosh and published by John Wiley & Sons. This book was released on 2021-06-01 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: A timely overview of fundamental and advanced topics of conjugated polymer nanostructures Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications is a comprehensive reference on conjugated polymers for energy applications. Distinguished academic and editor Srabanti Ghosh offers readers a broad overview of the synthesis, characterization, and energy-related applications of nanostructures based on conjugated polymers. The book includes novel approaches and presents an interdisciplinary perspective rooted in the interfacing of polymer and synthetic chemistry, materials science, organic chemistry, and analytical chemistry. This book provides complete descriptions of conjugated polymer nanostructures and polymer-based hybrid materials for energy conversion, water splitting, and the degradation of organic pollutants. Photovoltaics, solar cells, and energy storage devices such as supercapacitors, lithium ion battery electrodes, and their associated technologies are discussed, as well. Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications covers both the fundamental topics and the most recent advances in this rapidly developing area, including: The design and characterization of conjugated polymer nanostructures, including the template-free and chemical synthesis of polymer nanostructures Conjugated polymer nanostructures for solar energy conversion and environmental protection, including the use of conjugated polymer-based nanocomposites as photocatalysts Conjugated polymer nanostructures for energy storage, including the use of nanocomposites as electrode materials The presentation of different and novel methods of utilizing conjugated polymer nanostructures for energy applications Perfect for materials scientists, polymer chemists, and physical chemists, Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications also belongs on the bookshelves of organic chemists and any other practicing researchers, academics, or professionals whose work touches on these highly versatile and useful structures.

Download or read book Hybrid Perovskite Solar Cells written by Hiroyuki Fujiwara and published by John Wiley & Sons. This book was released on 2022-01-10 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unparalleled coverage of the most vibrant research field in photovoltaics! Hybrid perovskites, revolutionary game-changing semiconductor materials, have every favorable optoelectronic characteristic necessary for realizing high efficiency solar cells. The remarkable features of hybrid perovskite photovoltaics, such as superior material properties, easy material fabrication by solution-based processing, large-area device fabrication by an inkjet technology, and simple solar cell structures, have brought enormous attentions, leading to a rapid development of the solar cell technology at a pace never before seen in solar cell history. Hybrid Perovskite Solar Cells: Characteristics and Operation covers extensive topics of hybrid perovskite solar cells, providing easy-to-read descriptions for the fundamental characteristics of unique hybrid perovskite materials (Part I) as well as the principles and applications of hybrid perovskite solar cells (Part II). Both basic and advanced concepts of hybrid perovskite devices are treated thoroughly in this book; in particular, explanatory descriptions for general physical and chemical aspects of hybrid perovskite photovoltaics are included to provide fundamental understanding. This comprehensive book is highly suitable for graduate school students and researchers who are not familiar with hybrid perovskite materials and devices, allowing the accumulation of the accurate knowledge from the basic to the advanced levels.