Download or read book Controlling the Electronic Interface Properties in Polymer Fullerene Bulk Heterojunction Solar Cells written by Tobias Stubhan and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Elementary Processes in Organic Photovoltaics written by Karl Leo and published by Springer. This book was released on 2016-12-20 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents the results of a multi-year research programme funded by the Deutsche Forschungsgemeinschaft (German Research Council), which explains how organic solar cells work. In this new promising photovoltaic technology, carbon-based materials are deposited by low-cost methods onto flexible substrates, thus allowing devices which open completely new applications like transparent coatings for building, solar cells integrated into clothing or packages, and many more. The investigation of organic solar cells is an interdisciplinary topic, covering physics, chemistry and engineering. The different chapters address topics ranging from the synthesis of new organic materials, to the characterization of the elementary processes such as exciton transport and separation, and the principles of highly efficient device design. /div

Download or read book Organic Solar Cells written by Wallace C.H. Choy and published by Springer Science & Business Media. This book was released on 2012-11-19 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic solar cells have emerged as new promising photovoltaic devices due to their potential applications in large area, printable and flexible solar panels. Organic Solar Cells: Materials and Device Physics offers an updated review on the topics covering the synthesis, properties and applications of new materials for various critical roles in devices from electrodes, interface and carrier transport materials, to the active layer composed of donors and acceptors. Addressing the important device physics issues of carrier and exciton dynamics and interface stability and novel light trapping structures, the potential for hybrid organic solar cells to provide high efficiency solar cells is examined and discussed in detail. Specific chapters covers key areas including: Latest research and designs for highly effective polymer donors/acceptors and interface materials Synthesis and application of highly transparent and conductive graphene Exciton and charge dynamics for in-depth understanding of the mechanism underlying organic solar cells. New potentials and emerging functionalities of plasmonic effects in OSCs Interface Degradation Mechanisms in organic photovoltaics improving the entire device lifetime Device architecture and operation mechanism of organic/ inorganic hybrid solar cells for next generation of high performance photovoltaics This reference can be practically and theoretically applied by senior undergraduates, postgraduates, engineers, scientists, researchers, and project managers with some fundamental knowledge in organic and inorganic semiconductor materials or devices.

Download or read book Solar Cells Based on Colloidal Nanocrystals written by Holger Borchert and published by Springer Science & Business Media. This book was released on 2014-04-01 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a new system of solar cells. Colloidal nanocrystals possess many physical and chemical properties which can be manipulated by advanced control over structural features like the particle size. One application field is photovoltaics where colloidal semiconductor nanocrystals are explored as components of photo-active layers which can be produced from liquid media, often in combination with conductive polymers. The further development of this interdisciplinary field of research requires a deep understanding of the physics and chemistry of colloidal nanocrystals, conducting polymers and photovoltaic devices. This book aims at bridging gaps between the involved scientific disciplines and presents important fundamentals and the current state of research of relevant materials and different types of nanoparticle-based solar cells. The book will be of interest to researchers and PhD students. Moreover, it may also serve to accompany specialized lectures in related areas.

Download or read book Electronic Structure of Conjugated Materials and Their Effect on Organic Photovoltaics written by Chuanfei Wang and published by Linköping University Electronic Press. This book was released on 2017-11-15 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: The great tunability of structure and electronic properties of ?-conjugated organic molecules/polymers combined with other advantages such as light weight and flexibility etc., have made organic-based electronics the focus of an exciting still-growing field of physics and chemistry for more than half a century. The application of organic electronics has led to the appearance of wide range of organic electronic devices mainly including organic light emitting diodes (OLED), organic field effect transistors (OFET) and organic solar cells (OSC). The application of the organic electronic devices mainly is limited by two dominant parameters, i.e., their performance and stability. Up to date, OLED has been successfully commercialized in the market while the OSC are still on the way to commercialization hindered by low efficiency and inferior stability. Understanding the energy levels of organic materials and energy level alignment of the devices is crucial to control the efficiency and stability of the OSC. In this thesis, energy levels measured by different methods are studied to explore their relationship with device properties, and the strategies on how to design efficient and stable OSC based on energy level diagrams are provided. Cyclic Voltammetry (CV) is a traditional and widely used method to probe the energy levels of organic materials, although there is little consensus on how to relate the oxidation/reduction potential ((Eox/Ered) to the vacuum level. Ultraviolet Photoelectron Spectroscopy (UPS) can be used to directly detect vertical ionization potential (IP) of organic materials. In this thesis, a linear relationship of IP and Eox was found, with a slope equal to unity. The relationship provides for easy conversion of values obtained by the two techniques, enabling complementarily use in designing and fabricating efficient and stable OSC. A popular rule of thumb is that the offset between the LUMO levels of donor and acceptor should be 0.3 eV, according to which a binary solar cell with the minimum voltage losses around 0.49 V was designed here. Introduction of the ternary blend as active layer is an efficient way to improve both efficiency and stability of the OSC. Based on our studied energy-level diagram within the integer charge transfer (ICT) model, we designed ternary solar cells with enhanced open circuit voltage for the first time and improved thermal stability compared to reference binary ones. The ternary solar cell with minimum voltage losses was developed by combining two donor materials with same ionization potential and positive ICT energy while featuring complementary optical absorption. Furthermore, the fullerene acceptor was chosen so that the energy of the positive ICT state of the two donor polymers is equal to the energy of negative ICT state of the fullerene, which can enhance dissociation of all polymer donor and fullerene acceptor excitons and suppress bimolecular and trap-assistant recombination. Rapid development of non-fullerene acceptors in the last two years affords more recipes of designing both efficient and stabile OSC. We show in this thesis how non-fullerene acceptors successfully can be used to design ternary solar cells with both enhanced efficiency and thermal stability. Besides improving the efficiency of the devices, understanding of the stability and degradation mechanism is another key issue. The degradation of conjugated molecules/polymers often follow many complicated pathways and at the same time many factors for degradation are coupled with each other. Therefore, the degradation of non-fullerene acceptors was investigated in darkness by photoelectron spectroscopy in this thesis with the in-situ method of controlling exposure of O2 and water vapor separately.

Download or read book Controlling the Morphology of Solution processed Bulk Heterojunction Photovoltaics written by Kevin Andrew Sivula and published by . This book was released on 2007 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Polymer Solar Cells Molecular Design and Microstructure Control written by Kui Zhao and published by Frontiers Media SA. This book was released on 2020-12-10 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.

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 Determination Via Computational Modeling of the Structure properties Relationships in Intercalated Polymer written by Eunkyung Cho and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In bulk-heterojunction solar cells, device performance is influenced by both the intrinsic properties of the individual components - typically conjugated polymers and fullerene derivatives - and how they assemble and interact at their interface. The ability of fullerene to intercalate within the side-chains of a conjugated polymer can significantly affect the microstructure and overall device performance. Here, a series of computational chemistry approaches are applied to investigate the relationships between structure and property in intercalated polymer:fullerene blend. Using a combination of molecular mechanics (MM) calculation and simulations of 2D grazing incidence X-ray diffraction (GIXD) patterns, we have determined the molecular packing configuration of poly (2,5-bis (3-tetradecyl thiophene-2-yl) thieno[3,2-b]thiophene) (PBTTT-C14) and a blend of PBTTT-C14 and [6,6]-phenyl-C--1-butyric acid methyl ester (PC--1BM). Based on the confirmed packing structures, the electronic properties and morphological disorder were examined using density functional theory (DFT) and molecular dynamics (MD) calculations, respectively; we also investigated the intermolecular interaction energies behind the structure formation. Finally, we examined the vibrational, redox, and optical properties of the pristine polymer and a series of fullerene derivatives to understand the characteristic modes related to the various charged states of the systems.

Download or read book Photon Management in Solar Cells written by Ralf B. Wehrspohn and published by John Wiley & Sons. This book was released on 2016-03-09 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by renowned experts in the field of photon management in solar cells, this one-stop reference gives an introduction to the physics of light management in solar cells, and discusses the different concepts and methods of applying photon management. The authors cover the physics, principles, concepts, technologies, and methods used, explaining how to increase the efficiency of solar cells by splitting or modifying the solar spectrum before they absorb the sunlight. In so doing, they present novel concepts and materials allowing for the cheaper, more flexible manufacture of solar cells and systems. For educational purposes, the authors have split the reasons for photon management into spatial and spectral light management. Bridging the gap between the photonics and the photovoltaics communities, this is an invaluable reference for materials scientists, physicists in industry, experimental physicists, lecturers in physics, Ph.D. students in physics and material sciences, engineers in power technology, applied and surface physicists.

Download or read book Organic Solar Cells written by Masahiro Hiramoto and published by Springer Nature. This book was released on 2020-12-16 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the essential scientific ideas and breakthroughs in the last three decades for organic solar cells that have realized practical applications. The motivation for publishing this book is to explain how those essential ideas have arisen and to provide a foundation for future progress by target readers—students, novices in the field, and scientists with expertise. The main topics covered in the book include the fundamental principles and history of organic solar cells, blended junction, nanostructure control, photocurrent generation, photovoltage generation, doping, practical organic solar cells, and possible ideas for the future. The editors enthusiastically anticipate the vigorous development of the field of organic solar cells by young scientists of the next generation.

Download or read book Organic and Hybrid Solar Cells written by Hui Huang and published by Springer. This book was released on 2014-11-25 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book delivers a comprehensive evaluation of organic and hybrid solar cells and identifies their fundamental principles and numerous applications. Great attention is given to the charge transport mechanism, donor and acceptor materials, interfacial materials, alternative electrodes, device engineering and physics, and device stability. The authors provide an industrial perspective on the future of photovoltaic technologies.

Download or read book Unimolecular and Supramolecular Electronics I written by Robert M. Metzger and published by Springer Science & Business Media. This book was released on 2012-01-10 with total page 317 pages. Available in PDF, EPUB and Kindle. Book excerpt: Charge Transport in Organic Semiconductors, by Heinz Bässler and Anna Köhler. Frontiers of Organic Conductors and Superconductors, by Gunzi Saito and Yukihiro Yoshida. Fullerenes, Carbon Nanotubes, and Graphene for Molecular Electronics, by Julio R. Pinzón, Adrián Villalta-Cerdas and Luis Echegoyen. Current Challenges in Organic Photovoltaic Solar Energy Conversion, by Cody W. Schlenker and Mark E. Thompson.- Molecular Monolayers as Semiconducting Channels in Field Effect Transistors, by Cherie R. Kagan. Issues and Challenges in Vapor-Deposited Top Metal Contacts for Molecule-Based Electronic Devices, by Masato M. Maitani and David L. Allara. Spin Polarized Electron Tunneling and Magnetoresistance in Molecular Junctions, by Greg Szulczewski.

Download or read book Polymer Photovoltaics written by Fei Huang and published by Royal Society of Chemistry. This book was released on 2015-09-08 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymer solar cells have gained much attention as they offer a potentially economic and viable way of commercially manufacturing lightweight, flexible and low-cost photovoltaics. With contributions from leading scientists, Polymer Photovoltaics provides an international perspective on the latest research for this rapidly expanding field. The book starts with an Introduction to polymer solar cells and covers several important topics that govern their photovoltaic properties including the chemistry and the design of new light harvesting and interfacial materials and their structure-property relationship; the physics for photocurrent generation in the polymer solar cells; new characterization tools to study morphology effect on the property of donor/acceptor bulk heterojunctions; new device concepts such as tandem cells and semi-transparent cells and advanced roll-to-roll processes for large-scale manufacturing of polymer solar cells. Written by active researchers, the book provides a comprehensive overview of the recent advancements in polymer solar cell technology for both researchers and students that are interested in this field.

Download or read book Comprehensive Energy Systems written by Ibrahim Dincer and published by Elsevier. This book was released on 2018-02-07 with total page 5543 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Energy Systems, Seven Volume Set provides a unified source of information covering the entire spectrum of energy, one of the most significant issues humanity has to face. This comprehensive book describes traditional and novel energy systems, from single generation to multi-generation, also covering theory and applications. In addition, it also presents high-level coverage on energy policies, strategies, environmental impacts and sustainable development. No other published work covers such breadth of topics in similar depth. High-level sections include Energy Fundamentals, Energy Materials, Energy Production, Energy Conversion, and Energy Management. Offers the most comprehensive resource available on the topic of energy systems Presents an authoritative resource authored and edited by leading experts in the field Consolidates information currently scattered in publications from different research fields (engineering as well as physics, chemistry, environmental sciences and economics), thus ensuring a common standard and language

Download or read book Handbook of Organic Materials for Electronic and Photonic Devices written by Oksana Ostroverkhova and published by Woodhead Publishing. This book was released on 2018-11-30 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Organic Materials for Electronic and Photonic Devices, Second Edition, provides an overview of the materials, mechanisms, characterization techniques, structure-property relationships, and most promising applications of organic materials. This new release includes new content on emerging organic materials, expanded content on the basic physics behind electronic properties, and new chapters on organic photonics. As advances in organic materials design, fabrication, and processing that enabled charge unprecedented carrier mobilities and power conversion efficiencies have made dramatic advances since the first edition, this latest release presents a necessary understanding of the underlying physics that enabled novel material design and improved organic device design. - Provides a comprehensive overview of the materials, mechanisms, characterization techniques, and structure property relationships of organic electronic and photonic materials - Reviews key applications, including organic solar cells, light-emitting diodes electrochemical cells, sensors, transistors, bioelectronics, and memory devices - New content to reflect latest advances in our understanding of underlying physics to enable material design and device fabrication