Download or read book Study of Structure property performance Relationships for Organic Thin film Transistors and Polymeric Solar Cells written by Sheng Bi and published by . This book was released on 2016 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic electronics has great potential for fabricating low cost, flexible and large-area devices. Despite the rapid development, several main challenges of the field need to be addressed in both organic conjugated polymer and small molecules based devices, including organic thin-film transistors (OTFTs) and polymer solar cells (PSCs). This dissertation first explores two approaches to align small molecule crystals and improve surface coverage. The controlled evaporative self-assembly (CESA) method is combined with binary solvent system using small molecule SMDPPEH to control the crystal growth. By optimizing the two solvent ratios, well-aligned SMDPPEH crystals with significantly improved areal coverage were achieved. Also, polymer additives can be added into small molecule to control crystal alignment. As a result, mobilities are at least 10 times higher than that from spin-coated film. The SMDPPEH based OTFTs exhibit a mobility of 1.6×10-2 cm2/Vs, which is the highest mobility from SMDPPEH ever reported. The donor-acceptor vertical composition profile on the performance of the P3HT/PCBM based organic bulk heterojunction solar cells was studied. In this simulation study, variety of donor-acceptor vertical configurations was investigated for both regular and inverted PSC structures. The physical mechanisms behind the diversification of open circuit voltage, short circuit current, and fill factor, and thus power conversion efficiency from various vertical configurations are explained. The effect of vertical composition profile from the study could serve as guidance for experimental optimization of organic bulk heterojunction solar cells. Also, morphology variation of ZnO electron transport layer from atomic layer deposition and sol-gel methods on the performance of organic inverted solar cells were investigated. AFM and SEM were utilized to characterize the morphology of ZnO thin films and nanorods so as to explain the efficiency difference. The final part of the work demonstrates one-step multi-layer pattern transfer to make organic solar cells on rigid and flexible substrates. A multi-layer inking and stamping, a cost-efficient, purely additive pattern transfer technique, was developed to fabricate PSCs. GLYMO is added into PEDOT:PSS hole transport layer and its effect on PSC performance and pattern transfer yield was investigated to reach overall PSC efficiency and high yield pattern transfer.

Download or read book Design Synthesis and Structure Property Relationship Study of Polymer Field Effect Transistors written by Ting Lei and published by Springer. This book was released on 2015-01-05 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book summarizes Ting Lei’s PhD study on a series of novel conjugated polymers for field-effect transistors (FETs). Studies contain many aspects of polymer FETs, including backbone design, side-chain engineering, property study, conformation effects and device fabrication. The research results have previously scattered in many important journals and conferences worldwide. The book is likely to be of interest to university researchers, engineers and graduate students in materials sciences and chemistry who wish to learn some principles, strategy, and applications of polymer FETs.

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 Process structure property relationship of polymer fullerene bulk heterojunction films for organic solar cells written by Benjamin Schmidt-Hansberg and published by Cuvillier Verlag. This book was released on 2012-05-09 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic (PV) is attracting increasing interest as an important contribution to renewable energy supply. Organic photovoltaic (OPV) is a comparable young PV technology with a great potential towards low cost solar power. This is due to the intrinsic advantage of the incorporated organic semiconductors which are soluble. Solution processing allows high throughput coating and printing processes. Hence, energy intensive high temperature and vacuum steps can be avoided which reduces the fabrication costs and keeps energy payback times low. The performance of organic solar cells strongly depends on the structure of the solution cast photoactive layer which comprises a polymer-fullerene blend. The blend structure evolves during the film drying step which has been studied in this thesis. Starting point of this work was the hypothesis that drying process parameters are suitable for systematically tuning the structure formation during drying of solution cast polymer-fullerene films in order to generate optimized structures with improved photovoltaic performance. For the evaluation of this hypothesis the structure formation of the polymer-fullerene system Poly(3-hexylthiophene-2,5-diyl):[6,6]-Phenyl C61-butyric acid methyl ester (P3HT:PCBM) was investigated incorporating i) thin film drying kinetics, ii) phase behavior of polymer-fullerene solutions, iii) structure formation and iv) the drying process-structure-property relationship of solar cells. The generality of the obtained results has been studied in comparison with the behavior of Poly{[4,40-bis(2-ethylhexyl)dithieno(3,2-b;20,30-d)silole]-2,6-diyl-alt-(2,1,3-benzothidiazole)-4,7-diyl} (PSBTBT). i) Within this thesis a dedicated coating and drying setup was developed which afforded precisely defined coating and drying process conditions as prerequisite for all obtained results. For the first time, the drying behavior of finally a few hundred nanometer thin films could be investigated at five measurement positions with laser reflectometry simultaneously. This allowed the elaboration of a spatially resolved numerical thin film drying model. ii) In conjunction with the measurement and simulation of the evolution of film composition it was required to determine important instants of phase transitions such as solubility limits. Therefore the binodal region of P3HT solutions has been determined in the temperature range of 0°C-60°C. Within the unstable region P3HT solutions phase separate into a sol and a gel phase. The fullerene PCBM exhibits only a single solubility limit. iii) In order to correlate the expected phase transitions according to the phase diagrams with the real structure formation, the above mentioned coating and drying setup was combined with synchrotron based in situ grazing incidence X-ray diffraction (GIXD) measurements. This gave unique insights into the mechanisms and dynamics of polymer-fullerene blend crystallization. After reaching P3HT solubility the crystallization proceeded with well-oriented interface-induced P3HT nucleation followed by P3HT crystal growth with increasing orientation distribution of the crystallites and PCBM aggregation in the final drying period. Furthermore strong polymer-fullerene interaction forces could be derived. By increasing the PCBM fraction it could be shown for the 1:2 P3HT:PCBM ratio that PCBM molecules brake the (020) π-π-stacking of P3HT lamellae which signifies a dramatic loss of hole mobility and consequently reduced device performance. It is further notable that increasing drying temperatures reduce the amount of (020) π-π-stacked P3HT molecules but lead to an increased amount of P3HT (100) crystallinity. Hence, drying temperature determines the preferred direction of crystal growth. iv) Besides a finer degree of phase separation, reduced drying temperatures also cause a higher amount of π-π-stacked polymers, longer effective polymer conjugation length, increased amount of vertical charge transport pathways and an increasingly rough topography due to larger polymer aggregates. Jointly this leads to improved power conversion efficiency at lower drying temperatures. Based on the elaborated knowledge a strategy for a 40% reduction of drying time with only small drawbacks in solar cell performance could be developed. Finally it was important to investigate the transferability of the obtained knowledge to other material systems. PSBTBT:PC71BM blends show similarities to that of P3HT:PCBM with partly interface induced polymer nucleation and subsequent fullerene aggregation in the final drying stage. The kinetics of molecular ordering however proceed fast enough such that the drying process under the investigated conditions cannot limit the structure formation. Hence, P3HT:PCBM is a suitable model system due to its sensitivity to many process parameters. According to the process influence on novel materials the results of this thesis can serve as a source for appropriate process strategies.

Download or read book Organic Thin Film Transistor Integration written by Flora Li and published by John Wiley & Sons. This book was released on 2011-03-21 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on organic electronics (or plastic electronics) is driven by the need to create systems that are lightweight, unbreakable, and mechanically flexible. With the remarkable improvement in the performance of organic semiconductor materials during the past few decades, organic electronics appeal to innovative, practical, and broad-impact applications requiring large-area coverage, mechanical flexibility, low-temperature processing, and low cost. Thus, organic electronics appeal to a broad range of electronic devices and products including transistors, diodes, sensors, solar cells, lighting, displays, and electronic identification and tracking devices A number of commercial opportunities have been identified for organic thin film transistors (OTFTs), ranging from flexible displays, electronic paper, radio-frequency identification (RFID) tags, smart cards, to low-cost disposable electronic products, and more are continually being invented as the technology matures. The potential applications for "plastic electronics" are huge but several technological hurdles must be overcome. In many of these applications, transistor serves as a fundamental building block to implement the necessary electronic functionality. Hence, research in organic thin film transistors (OTFTs) or organic field effect transistors (OFETs) is eminently pertinent to the development and realization of organic electronics. This book presents a comprehensive investigation of the production and application of a variety of polymer based transistor devices and circuits. It begins with a detailed overview of Organic Thin Film Transistors (OTFTs) and discusses the various possible fabrication methods reported so far. This is followed by two major sections on the choice, optimization and implementation of the gate dielectric material to be used. Details of the effects of processing on the efficiency of the contacts are then provided. The book concludes with a chapter on the integration of such devices to produce a variety of OTFT based circuits and systems. The key objective is to examine strategies to exploit existing materials and techniques to advance OTFT technology in device performance, device manufacture, and device integration. 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. Overall, a major outcome of this work is that it provides an economical means for organic transistor and circuit integration, by enabling the use of a well-established PECVD infrastructure, while not compromising the performance of electronics. The techniques established here are not limited to use in OTFTs only; the organic semiconductor and SiNx combination can be used in other device structures (e.g., sensors, diodes, photovoltaics). Furthermore, the approach and strategy used for interface optimization can be extended to the development of other materials systems.

Download or read book A Structure property performance Relationship Study on Highly Efficient Organic Solar Cells written by Yunke Li and published by . This book was released on 2019 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microwave assisted Polymer Synthesis written by Richard Hoogenboom and published by Springer. This book was released on 2016-09-02 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Advances in Polymer Science presents critical reviews of the present and future trends in polymer and biopolymer science. It covers all areas of research in polymer and biopolymer science including chemistry, physical chemistry, physics, material science.The thematic volumes are addressed to scientists, whether at universities or in industry, who wish to keep abreast of the important advances in the covered topics.Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.Review articles for the individual volumes are invited by the volume editors. Single contributions can be specially commissioned.Readership: Polymer scientists, or scientists in related fields interested in polymer and biopolymer science, at universities or in industry, graduate students

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 Morphology Control Strategies to Enable Printable Solar Cells written by Sebastian Alexander Schneider and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapidly decarbonizing our way of life, parti¬cularly the way we generate power, will be critical to mitigate the potentially catastrophic effects of climate change. Time is of the essence and low-cost and scaleable energy technologies that are equitable can play a key role in these efforts. Organic photovoltaics (OPVs) are an emerging technology based on semiconducting organic polymers and molecules with many potential benefits, such as low weight, flexibility, and printability. In recent years, the performance of research level OPVs has significantly increased, closing the gap to established silicon solar cell technologies. Arguably, printability is one of the key advantages of OPVs, as it can facilitate high-throughput production at extremely low cost. Yet, producing high efficiency OPVs with scaleable production methods such as roll-to-roll (R2R) printing is a key challenge that remains on the path to commercialization and implementation of OPVs. This is largely due to the fact that the efficiency of OPVs strongly depends on the complex microstructure -- also referred to as morphology -- of the active layer that converts light into electricity. Controlling the self-assembly of the materials during printing is significantly more challenging on the industrial scale than on the lab scale. In this thesis, three morphology control strategies are developed that enable direct transfer to scaleable printing techniques while maintaining high solar cell efficiencies. The focus of this work is on developing structure-performance relationships using a suite of synchrotron X-ray scattering techniques for in-depth morphological characterizations. Further, we use these techniques to study the self-assembly of the active layer in real-time during printing and provide mechanistic insight on how different morphology control strategies can be leveraged to optimize the morphology and thereby the performance of printed OPVs. First, a high-level introduction outlines the challenge of rapid decarbonization and the role emerging solar cell technologies such as OPVs can play in addressing this challenge. Special emphasis is placed on the challenge of scaleability on the path to commercialization of OPVs. Chapter 2 provides relevant theoretical background on the three key areas relevant to this thesis research. (I) Organic solar cells, (II) X-ray characterization techniques for organic thin films, and (III) scaleable printing techniques for organic solar cells. Chapter 3 describes a systematic side-chain engineering molecular design approach to control the self-aggregation of a widely used OPV acceptor polymer enabling high performance printable all-polymer solar cells. We find that a balanced propensity of donor and acceptor to self-aggregate is key to achieve intrinsic printability for this material system. Specifically, we show a simple yet effective way to modulate the self-aggregation of the commonly used naphthalene diimide (NDI)-based acceptor polymer (N2200) by systematically replacing a certain amount of alkyl side-chains with compact bulky side-chains (CBS) resulting in a series of random copolymer (PNDI-CBSx) with different molar fractions. Both solution-phase aggregation and solid-state crystallinity of these acceptor polymers are increasingly suppressed with increasing molar fractions of the CBS side-chain. We find that balanced aggregation strength between the donor and acceptor polymers is critical to achieve high-performance (up to 8.5% efficient) all-PSCs with optimal active layer film morphology. Further, we show that balanced aggregation strength of donor and acceptor yields an active layer morphology that is less sensitive to the film deposition methods and solution coating can be achieved without performance losses. Chapter 4 showcases the systematic fluorination of a PBDB-TFy donor and PNDI-TFx acceptor polymer (x, y = 0, 50, 75, 100) and discusses the impact active layer morphology and device performance. We find that fluorination of donor and acceptor polymers does not significantly alter the crystallinity of the respective neat polymers but results in increased compatibility -- in terms of reduced Flory-Huggins interaction parameter -- of the materials. We observe a systematic increase of device performance with increased extent of fluorination. Morphological studies reveal that this improvement largely stems from a more favorable blend morphology with reduced domain size. Specifically, we characterize the domain size of the best performing blend PBDB-TF100:PNDI-TF100 in detail with RSoXS and HRTEM techniques. We observe good agreement between both techniques yielding a domain size close to 30 nm representing a significantly reduce phase separation compare to the non-fluorinated control system PBDB-TF0:PNDI-TF0. Further, we explore the device optimization of this system with the commonly used DIO additive in detail and find that DIO selectively interacts with the donor polymer leading to increased face-on texture crystallinity, further improving the fill factor of the solar cells. Chapter 5 provides in-depth mechanistic insight into the in-situ morphology evolution of all-polymers solar cell systems during scaleable printing. We demonstrate how non-covalent interactions between donor and acceptor polymers can be leveraged to achieve a morphology evolution that is insensitive to changes in the drying conditions and that translates exceptionally well to printing fabrication. Specifically, we systematically control the donor-acceptor interactions using different extents of fluorination of PDBD-TFy and PNDI-TFx (x, y = 0, 0.5, 1.0) donor and acceptor polymers. We show that donor-acceptor interactions can induce donor crystallization, facilitating a high solar cell fill factor (0.65) and excellent transferability to printing fabrication. Leveraging this molecular design strategy, we fabricate printed devices with up to 6.82 % efficiency (compared to the 3.61 % efficient control system). Chapter 6 showcases a novel solvent additive approach based on phthalate additives to control polymer crystallinity and suppress unfavorable phase separation in a representative PTB7-Th/P(NDI2OD-2T) all-polymer solar cell. The best-performing additive increased the blade-coated device performance from 2.09 to 4.50% power conversion efficiency, an over two-fold improvement, mitigating the loss in performance that is typically observed during process transfer from spin-coating to blade-coating. We find that the improved device performance stems from a finer polymer phase-separation size and overall improved active layer morphology. Real-time X-ray diffraction measurements during blade-coating provide mechanistic insights and suggest that the dioctyl phthalate additive may act as a compatibilizer, reducing the demixing of the donor and acceptor polymer during film formation, enabling a smaller phase separation and improved performance. Chapter 7 concludes this thesis with a summary of key conclusions and future directions of this work. Specifically, mixed phase characterization and morphology evolution of polymer:NFA systems, potential morphology control strategies for state-of-the-art all-polymer solar cells, and solvent quality and temperature aggregation studies are briefly discussed. Lastly, the appendix to this thesis provides an overview of selected examples of structural characterization of functional organic thin films to develop structure-property relations in organic solar cells and adjacent field such as organic field effect transistors (OFETs).

Download or read book Structure property performance Relationships for Organic Photovoltaics and the Utilization of Photoconducting Atomic Force Microscopy for Characterizing Organic Thin Films written by Michele Elyse Guide and published by . This book was released on 2014 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: Altogether, this work demonstrates the importance of developing structure-property-performance relationships, provides insight to the continued improvement of OPV performance, and sets the groundwork for the reliable utilization of pc-AFM as a technique for characterizing organic thin films.

Download or read book Structure Processing Relationships in Solution Processable Polymer Thin Film Transistors and Small Molecule Bulk Heterojunction Solar Cells written by Louis A. Perez and published by . This book was released on 2014 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solution processed organic photovoltaic devices (OPVs) have emerged as a promising sustainable energy technology due to their ease of fabrication, potential to enable low-cost manufacturing, and ability to be incorporated onto light-weight flexible substrates. To date, the most efficacious OPV device architecture, the bulk heterojunction (BHJ), consists of a blend of a light-harvesting conjugated organic electron donating molecule and a strong electron-accepting compound (usually a soluble fullerene derivative e.g. [6,6]-phenyl C71 butyric acid methyl ester (PC71BM).

Download or read book An Investigation of the Structure property performance Relationship for Organic Semiconductors in Polymer and Electrolyte gated Organic Field effect Transistors written by Raja Khan and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design and Growth of Organic Semiconductors for Organic Thin Film Transistors written by Vladimir Aleksandrovich Pozdin and published by . This book was released on 2011 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic field-effect transistors are attracting much attention due to possible applications in flexible electronics, but low electronic performance and stability remain challenges to realizing such applications. Nevertheless, molecular semiconductors have already been successfully integrated in commercial products such as organic displays, luminaires, and photovoltaics. While polymeric materials have historically lagged behind, they are currently gaining significant attention due to their ease of processing, which does not require a vacuum deposition system. Polymeric materials present a number of challenges, from designing the structure of the monomer to finding the optimum molecular weight. We present an exhaustive structure-property relationship study of a newly synthesized family of thienoacenes. Based on the results of our study, we suggest C2 symmetry for the repeat unit as a new design criterion to aid in the development of future polymeric semiconductors. In addition, we investigate the thermal stability of our polymers using ex-situ and in-situ X-ray scattering. We identify an irreversible reorganization due to solution processing, as well as a reversible thermal expansion with linear expansion coefficient of 2x10-4 °C-1. By optimizing polymer structure and processing conditions, we have achieved a field-effect hole mobility of 0.3 cm2/Vs and environmental stability exceeding one year. Even though molecular electronics, such as OLEDs with AlQ3, have already been commercialized, the fundamental questions of charge transport and trapping have not been answered for these materials, owing to the high degree of anisotropy in molecular thin films. We report an unexpected reorganization of molecular thin films of pentacene on commonly used SiO2 substrates treated with a self-assembled monolayer under inert conditions. In addition, we investigated the process of solvent annealing of an insoluble molecular semiconductor. The method of solvent annealing is further demonstrated as a feasible process to improve crystallinity in organic films without the adverse effects of thermal annealing.

Download or read book Semiconductor Materials and Modelling for Solar Cells written by Z. Pezeshki and published by Materials Research Forum LLC. This book was released on 2021-07-05 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book presents a comprehensive survey about advanced solar cell technologies. Focus is placed on semiconductor materials, solar cell efficiency, improvements in surface recombination velocity, charge density, high ultraviolet (UV) sensitivity, modeling of solar cells etc. The book references 281 original resources with their direct web links for in-depth reading. Keywords: Solar Cells, Thin Film Solar Cells, Solar Cell Efficiency, Semiconductor Materials, Surface Recombination Velocity, Charge Density, High UV Sensitivity, Heavily-doped Silicon Wafers, Amorphous Semiconductors, Nanocrystalline Semiconductors, Field Effect, Ferroelectric Semiconductors, Solar Cell Modelling.

Download or read book Understanding Organic Thin Film Properties for Microelectronic Organic Field effect Transistors and Solar Cells written by Luke Bennett Roberson and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this work is to understand how the thin film characteristics of p-type organic and polymer semiconductors affect their electronic properties in microelectronic applications. To achieve this goal, three main objectives were drawn out: (1) to create single-crystal organic field-effect transistors and measure the intrinsic charge carrier mobility, (2) to develop a platform for measuring and depositing polymer thin films for organic field-effect transistors, and (3) to deposit polythiophene thin films for inorganic-organic hybrid solar cells and determine how thin film properties effect device performance. Pentacene single-crystal field-effect transistors (OFETs) were successfully manufactured on crystals grown via horizontal vapor-phase reactors designed for simultaneous ultrapurification and crystal growth. These OFETs led to calculated pentacene field-effect mobility of 2.2 cm2/Vs. During the sublimation of pentacene at atmospheric pressure, a pentacene disporportionation reaction was observed whereby pentacene reacted with itself to form a peripentacene, a 2:1 cocrystal of pentacene:6,13-dihydropentacene and 6,13-dihydropentacene. This has led to the proposal of a possible mechanism for the observed disproportionation reaction similar to other polyaromatic hydrocarbons, which may be a precursor for explaining the formation of graphite. Several silicon-based and PET-based field-effect transistor platforms were developed for the measurement of mobility of materials in the thin film state. These platforms were critically examined against one another and the single-crystal devices in order to determine the optimal device design for highest possible mobility data, both theoretically based on silicon technology and commercially based on individual devices on flexible substrates. Novel FET device designs were constructed with a single gate per device on silicon and PET as well as the commonly used common-gate device. It was found that the deplanarization effects and poor gate insulator quality of the individual gate devices led to lower overall performance when compared to the common gate approach; however, good transistor behavior was observed with field modulation. Additionally, these thin films were implemented into inorganic-organic hybrid and purely organic solid-state photovoltaic cells. A correlation was drawn between the thin film properties of the device materials and the overall performance of the device. It was determined that each subsequent layer deposited on the device led to a planarization effect, and that the more pristine the individual layer, the better device performance. The hybrid cells performed at VOC = 0.8V and JSC = 55A/cm2.

Download or read book Structure Property Relationships in Semiconducting Polymers and Small Molecules Probed by Synchrotron X ray Methods written by Gregory M. Su and published by . This book was released on 2015 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic semiconductors are an exciting class of materials that have potential to produce low-cost, printable, and flexible electronic devices. Moving to the next generation of organic semiconductors that will result in greater efficiency requires advancements in the areas of materials chemistry, molecular assembly, predictive modelling, and device optimization. Here, we focus on morphology and demonstrate how it is linked to each of these areas. Understanding the connections among chemistry, thin film microstructure, and charge transport remains a major challenge in the field. We examined materials systems relevant to organic solar cells, memory devices, and transistors, with a focus on synchrotron-based X-ray techniques. For a blend of a polymer and small molecule, applicable to solar cells, control of molecular orientation in the small molecule is especially important for non-fullerene based molecules that exhibit anisotropic charge transport. In ferroelectric-semiconductor polymer blends used in organic memory, improved control over phase separation length scales is achieved by altering the chemistry of the semiconducting polymer to tune polymer-polymer interactions. Complementary simulations can facilitate characterization of organic semiconductors. First-principles predictions of X-ray absorption spectroscopy are applied to semiconducting polymers, and prove critical for understanding complex experimental data related to molecular orientation and electronic structure in general. Overall, these studies provide insights into key factors that should be considered in the development of new organic semiconductors.

Download or read book Physical Chemistry and Chemical Physics Editor s Pick 2021 written by Malgorzata Biczysko and published by Frontiers Media SA. This book was released on 2021-07-28 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: