Download or read book Organic Bulk Heterojunction Solar Cells with Improved Efficiency written by Yanfei Ding and published by . This book was released on 2010 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Organic Solar Cells written by Barry P. Rand and published by CRC Press. This book was released on 2014-08-26 with total page 795 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic photovoltaic (OPV) cells have the potential to make a significant contribution to the increasing energy needs of the future. In this book, 15 chapters written by selected experts explore the required characteristics of components present in an OPV device, such as transparent electrodes, electron- and hole-conducting layers, as well as elect
Download or read book Charge Collection and Surface Recombination Effects in Organic Bulk Heterojunction Solar Cells written by Buddika KA. Abeyweera and published by . This book was released on 2013 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: Charge transfer and charge extraction mechanisms are two prevalent issues in the growing field of organic solar cells. Due to their complexity in nature, new methods need to be involved in addressing the fundamental properties associated with organic polymer solar cells. This dissertation has focused on developing a new method to estimate the charge collection lengths and surface recombination lengths of organic polymer solar cells. Photocurrent spectra have been analyzed systematically to observe the dependence on thickness of the active material. A red shift of the peak of the normalized photocurrent with respect to the device thickness has been further analyzed for two major material systems used in organic polymer solar cells, namely MDMO-PPV: PCBM and P3HT: PCBM. A theoretical model that measures the charge extraction of bulk hetero junction solar cell structures has been used taking into account of three main parameters including charge carrier collection length, absorption variation and surface recombination. This model has led to estimate two important parameters associated with charge transfer, recombination and extraction of organic solar cells which will provide opportunities for improvements in the performance of organic electronic devices. Key results are summarized as follows. A complete analysis of photocurrent spectra has been done to see its variation with active material thickness of well-known two material systems of bulk heterojunction organic solar cells. Results of these preliminary measurements suggest that peak of the photocurrent for both systems red shift with increasing thickness. Charge extraction model is introduced to explain the initial red shift of the photocurrent. This model fits well with the experimental results. Further analysis of the model suggests that the charge collection lengths can be estimated for organic polymer structures. Theoretical model gives higher collections lengths for MDMO-PPV solar cells while a lower collection length for P3HT solar cells. This model also has the capability to estimate the surface recombination length of organic bulk heterojunction solar cells. Different interfacial layers have been used to fit to the model calculation. These results suggest that the least surface recombination lengths were achieved with solar cells of PEDOT-PSS. This method can be used to optimize the interfacial layers to improve the efficiency in organic solar cells. AC photocurrent measurements have been carried out to observe the frequency dependence of organic solar cells. Main results show that increasing response time from the light source increases the performance of the solar cells. Further analysis of these results suggests that thicker devices of organic polymer solar cells can be applied with longer response time light sources. Degradation of organic polymer solar cells over a period of several days has been carried out to observe the stability of solar cells with device thickness. Results suggest that the degradation occurs regardless of device thickness of the active material. A new probing technique called capacitive photocurrent spectroscopy (CPS) has been carried out with P3HT solar cells to observe the charge dissociation efficiency. The CPS measurements suggest that sub band gap states have higher dissociation efficiencies that may not contribute to overall photocurrent of the solar cells.
Download or read book Enhancement of the Performance of Bulk Heterojunction Solar Cell written by Lemessa Asefa Eressa and published by LAP Lambert Academic Publishing. This book was released on 2011-12 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: A solar cell is a photovoltaic device designed to convert sunlight into electrical power. We can categorize solar cells into organic and inorganic. The advantages of organic solar cell over inorganic ones are inexpensive to fabricate, light weight, flexible shape and have little potential for negative environmental impact.But, the disadvantages of organic solar cell is low power conversion efficiency and suffer from huge degradation.So, there are different approaches for improving the efficiency of organic solar cells. Some of them are selection of solar harvesting material which have low band gap and broad absorption, active layer structure design (such as using bulk heterojunction), and etc.This work is aimed at enhancing the performance of a bulk heterojunction solar cell made from APFO Green-6: PCBM (1:4 ratio).This can be achieved through creating new device architecture design(bulk heterojunction) and careful control on the morphology of the active layer using thermal annealing in order to get a higher power conversion efficiency. Thermal annealing increases the degree of crystallization of the cell, charge transport and then the efficiency of the organic cell.
Download or read book How Molecular Morphology Affects the Performance of Organic Solar Cells written by Jonathan Alan Bartelt and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic bulk heterojunction (BHJ) solar cells consisting of electron-donating polymers and electron-accepting fullerene derivatives garner interest because they can be manufactured inexpensively at high throughput via solution processing. The power conversion efficiency of BHJ solar cells is now above 11 and 12% in single-junction and tandem architectures, respectively. Much of the recent improvement in device performance is due to (i) the development of low band gap polymers with broad absorption capabilities, (ii) the development of polymers and fullerene derivatives with energy levels optimized for higher open-circuit voltages, and (iii) the use of solvent additives to tailor the BHJ morphology. Despite these improvements, the efficiency of single junction BHJ solar cells must surpass 15% before organic solar cells can compete with inorganic solar cells based on silicon or cadmium telluride. In this doctoral thesis, I examine how the polymer and fullerene morphology affect the performance of BHJ solar cells and determine how the efficiency of these devices can be improved. In Chapter 2, I show that the morphology of polymer-fullerene BHJs consists of three phases: pure polymer aggregates, pure fullerene clusters, and an amorphous phase consisting of polymer and fullerene mixed at the molecular level. The concentration of fullerene in the molecularly mixed phase has a strong influence on device performance. In order to have a fully percolated network of electron transporting fullerene molecules within the mixed regions, at least 20 weight percent fullerene must be mixed with the polymer. Decreasing the concentration of fullerene below this percolation threshold reduces the number of electron transport pathways within the mixed regions and creates morphological electron traps that enhance charge-carrier recombination and decrease device efficiency. In Chapter 3, I discuss how the polymer molecular weight plays a role in determining the final BHJ morphology and device efficiency. BHJs made with low molecular weight polymer have exceedingly large fullerene-rich domains. Increasing the molecular weight of the polymer decreases the size of these domains and significantly improves device efficiency. I show that polymer aggregation in solution affects the size of the fullerene-rich domains and determine that this effect is linked to the dependency of polymer solubility on molecular weight. Due to its poor solubility, high molecular weight polymer quickly aggregates in solution and forms a network that acts as a template and prevents large scale phase separation. Finally, I find that the performance of devices made with low molecular weight polymer can be improved by using solvent additives during processing to force the polymer to aggregate in solution. I examine how the efficiency of organic solar cells can be improved to 15% in Chapter 4. To surpass 15% efficiency, devices likely will need to be 300 nm thick and achieve fill factors near 0.8. Using a numerical device simulator, I show that the key to achieving these performance metrics is a high charge-carrier mobility and a low recombination rate constant. Devices with low charge-carrier mobility (10-2 cm2 V-1 s-1) suffer from high rates of bimolecular recombination because many charge carriers must reside in the device to drive a given drift current. Furthermore, I demonstrate that numerical device simulators are a powerful tool for investigating charge-carrier transport in BHJ devices and are useful for rapidly prototyping BHJ solar cells. To conclude, I discuss how researchers can improve the efficiency of organic solar cells. Researchers should aim to design molecular systems that exhibit high miscibility ( 20 weight percent fullerene in the mixed phase) or immiscibility (H" weight percent fullerene in the mixed phase). Furthermore, the synthesis of new, high molecular weight polymers with exceptionally high charge-carrier mobility and low recombination rate constants is imperative for reaching high device fill factor. With these improvements, the efficiency of organic solar cells can surpass 15%, which would allow these devices to compete with traditional inorganic solar cell technologies.
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 Comprehensive Guide on Organic and Inorganic Solar Cells written by Md. Akhtaruzzaman and published by Academic Press. This book was released on 2021-11-18 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Guide on Organic and Inorganic Solar Cells: Fundamental Concepts to Fabrication Methods is a one-stop, authoritative resource on all types of inorganic, organic and hybrid solar cells, including their theoretical background and the practical knowledge required for fabrication. With chapters rigorously dedicated to a particular type of solar cell, each subchapter takes a detailed look at synthesis recipes, deposition techniques, materials properties and their influence on solar cell performance, including advanced characterization methods with materials selection and experimental techniques. By addressing the evolution of solar cell technologies, second generation thin-film photovoltaics, organic solar cells, and finally, the latest hybrid organic-inorganic approaches, this book benefits students and researchers in solar cell technology to understand the similarities, differences, benefits and challenges of each device. Introduces the basic concepts of different photovoltaic cells to audiences from a wide variety of academic backgrounds Consists of working principles of a particular category of solar technology followed by dissection of every component within the architecture Crucial experimental procedures for the fabrication of solar cell devices are introduced, aiding picture practical application of the technology
Download or read book Bulk heterojunction Solar Cells written by K. Xerxes Steirer and published by . This book was released on 2010 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exciton Recombination in the Fullerene Phase of Bulk Heterojunction Organic Solar Cells written by George Frederick Burkhard and published by Stanford University. This book was released on 2011 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finding alternatives to fossil fuel energy sources is necessary to stem global warming, to provide economic and political independence, and to keep up with increasing energy demand. Because of their low cost, flexibility, and because the material resources needed to make them are abundant, organic polymer solar cells are an attractive alternative to conventional solar technology. Organic solar technology has been developing rapidly; however, with the best power conversion efficiencies at ~8%, much improvement is needed before it can be competitive with established solar technologies. Poly-3-hexylthiophene:[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) solar cells are the most studied type of organic solar cell. Nevertheless, their loss mechanisms are still not fully understood. In this work, we study excitonic losses in the PCBM phase of the blend. We develop a way to accurately measure internal quantum efficiencies (IQEs) and use this technique to characterize P3HT:PCBM devices. We observe spectral dependence of the IQE and conclude that a majority of excitons generated in the PCBM are lost to Auger recombination with polarons that are trapped in that phase. We also provide evidence that this process may happen in other materials and may be a critical factor in limiting exciton diffusion in organic semiconductors.
Download or read book Organic Solar Cells written by Qiquan Qiao and published by CRC Press. This book was released on 2017-12-19 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current energy consumption mainly depends on fossil fuels that are limited and can cause environmental issues such as greenhouse gas emissions and global warming. These factors have stimulated the search for alternate, clean, and renewable energy sources. Solar cells are some of the most promising clean and readily available energy sources. Plus, the successful utilization of solar energy can help reduce the dependence on fossil fuels. Recently, organic solar cells have gained extensive attention as a next-generation photovoltaic technology due to their light weight, mechanical flexibility, and solution-based cost-effective processing. Organic Solar Cells: Materials, Devices, Interfaces, and Modeling provides an in-depth understanding of the current state of the art of organic solar cell technology. Encompassing the full spectrum of organic solar cell materials, modeling and simulation, and device physics and engineering, this comprehensive text: Discusses active layer, interfacial, and transparent electrode materials Explains how to relate synthesis parameters to morphology of the photoactive layer using molecular dynamics simulations Offers insight into coupling morphology and interfaces with charge transport in organic solar cells Explores photoexcited carrier dynamics, defect states, interface engineering, and nanophase separation Covers inorganic–organic hybrids, tandem structure, and graphene-based polymer solar cells Organic Solar Cells: Materials, Devices, Interfaces, and Modeling makes an ideal reference for scientists and engineers as well as researchers and students entering the field from broad disciplines including chemistry, material science and engineering, physics, nanotechnology, nanoscience, and electrical engineering.
Download or read book Novel Acceptor Molecules for Bulk Heterojunction Organic Solar Cells written by Jason Thomas Bloking and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solution-processable organic solar cells offer the promise of clean energy generation at lower cost than conventional technologies due to high-throughput roll-to-roll manufacturing, cheap and abundant materials and the lower installation costs associated with lightweight and flexible solar modules. Power conversion efficiencies of organic solar cells have surpassed 10% due in large part to the discovery and design of new materials for the donor half of the donor-acceptor heterojunction. However, the vast majority of organic photovoltaic devices contain fullerene derivatives as the electron acceptor material. Devices containing fullerenes as the electron acceptors have been shown to be energetically limited to open-circuit voltages of 1.0 V or less, thus limiting their maximum efficiency and potential for use as the high-voltage top cell in tandem solar cell architectures. This is in addition to other drawbacks of fullerenes such as their high synthetic cost and relatively poor light absorption. A phenyl imide-based electron acceptor molecule, HPI-BT, has been developed as an alternative to fullerene derivatives to address some of these drawbacks. Device efficiencies of up to 3.7% with the common electron donating polymer poly (3-hexyl thiophene) -- P3HT -- have been achieved through detailed optimization. While these devices have open-circuit voltages of 0.94 V (0.31 V higher than comparable devices with P3HT and PC61BM, a common fullerene derivative), the quantum efficiency is 20% lower than the equivalent fullerene-containing device. Through investigation of the dependence of quantum efficiency on applied electric field and light intensity in these devices and others using additional electron donating polymers, the primary cause of lower quantum efficiency in these devices is found to be recombination of geminate charge pairs before they are able to reach their fully charge-separated state. Recent research reports show that the microstructure of a typical bulk heterojunction organic solar cell consists of a relatively pure electron donor phase (P3HT), a relatively pure acceptor phase (PC61BM) and a two-component mixed phase at the interface of the two pure phases. This interfacial mixed phase is believed to provide an energetic driving force for charge separation from the mixed phase into the pure phases, thus providing high quantum efficiencies in fullerene-based devices. X-ray diffraction studies on blends of polythiophene and HPI-BT show no evidence of a strongly mixed third phase. The lower quantum efficiency of devices containing HPI-BT without this third mixed phase is explained by the favorable energetic offsets created in this three-phase morphology. Alternatively, the inability of fullerenes to effectively absorb light can be partially mitigated by the addition of a third molecule providing additional absorption bandwidth in a ternary blend organic solar cell. The addition of up to 20% (by weight) of a conjugated dye molecule, tetra-tert-butyl functionalized silicon naphthalocyanine (t-butyl SiNc), to a typical bulk heterojunction solar cell with P3HT and PC61BM results in the generation of additional photocurrent from dye absorption in the near-infrared region of the light spectrum. The effect of the tert-butyl functionalization on the incorporation of the dye molecule is discussed along with the potential for improved efficiency of ternary blend organic solar cells relative to their binary blend counterparts.
Download or read book Organic Solar Cells written by Pankaj Kumar and published by CRC Press. This book was released on 2016-10-03 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains detailed information on the types, structure, fabrication, and characterization of organic solar cells (OSCs). It discusses processes to improve efficiencies and the prevention of degradation in OSCs. It compares the cost-effectiveness of OSCs to those based on crystalline silicon and discusses ways to make OSCs more economical. This book provides a practical guide for the fabrication, processing, and characterization of OSCs and paves the way for further development in OSC technology.
Download or read book Fundamentals of Solar Cell Design written by Inamuddin and published by John Wiley & Sons. This book was released on 2021-08-24 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar cells are semiconductor devices that convert light photons into electricity in photovoltaic energy conversion and can help to overcome the global energy crisis. Solar cells have many applications including remote area power systems, earth-orbiting satellites, wristwatches, water pumping, photodetectors and remote radiotelephones. Solar cell technology is economically feasible for commercial-scale power generation. While commercial solar cells exhibit good performance and stability, still researchers are looking at many ways to improve the performance and cost of solar cells via modulating the fundamental properties of semiconductors. Solar cell technology is the key to a clean energy future. Solar cells directly harvest energy from the sun’s light radiation into electricity are in an ever-growing demand for future global energy production. Solar cell-based energy harvesting has attracted worldwide attention for their notable features, such as cheap renewable technology, scalable, lightweight, flexibility, versatility, no greenhouse gas emission, environment, and economy friendly and operational costs are quite low compared to other forms of power generation. Thus, solar cell technology is at the forefront of renewable energy technologies which are used in telecommunications, power plants, small devices to satellites. Aiming at large-scale implementation can be manipulated by various types used in solar cell design and exploration of new materials towards improving performance and reducing cost. Therefore, in-depth knowledge about solar cell design is fundamental for those who wish to apply this knowledge and understanding in industries and academics. This book provides a comprehensive overview on solar cells and explores the history to evolution and present scenarios of solar cell design, classification, properties, various semiconductor materials, thin films, wafer-scale, transparent solar cells, and so on. It also includes solar cells’ characterization analytical tools, theoretical modeling, practices to enhance conversion efficiencies, applications and patents.
Download or read book Semiconducting and Metallic Polymers written by Alan J. Heeger and published by OUP Oxford. This book was released on 2010-07-29 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: The unique properties of conducting and semiconducting (conjugated) polymers make them one of the most attractive areas of interdisciplinary materials science and technology. Written by a pioneer in the field, this book is the first aimed at teaching graduate students, postdoctoral scientists, and specialists in industry about this exciting field.
Download or read book Organic Bulk heterojunction Photovoltaic Devices written by Margherita Bolognesi and published by . This book was released on 2013 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on organic photovoltaic devices (OPV) has developed during the past 30 years, but especially in the last decade it has attracted scientific and economic interest triggered by a rapid increase in power conversion efficiencies. Thanks to the introduction of the bulk heterojunction (BHJ) concept, today BHJ OPV efficiencies are exceeding 9%. This thesis gives an overview on the different possible strategies that could be adopted for a further. improvement of BHJ OPV devices performances. The accurate analysis of the chemical, energetic and physical criteria governing the solar cells functioning allowed to individuate some critical aspects and apply possible solutions by a fine tuning of the materials chemical structures, device processing techniques and device architecture engineering. Even though noit in all cases the applied strategy successfully led to device efficiency improvements, the fundamental understanding of some of the efficiency limiting factors could serve as useful scientific basis for future developments.
Download or read book Progress in High Efficient Solution Process Organic Photovoltaic Devices written by Yang Yang and published by Springer. This book was released on 2015-02-17 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an important technique to process organic photovoltaic devices. The basics, materials aspects and manufacturing of photovoltaic devices with solution processing are explained. Solution processable organic solar cells - polymer or solution processable small molecules - have the potential to significantly reduce the costs for solar electricity and energy payback time due to the low material costs for the cells, low cost and fast fabrication processes (ambient, roll-to-roll), high material utilization etc. In addition, organic photovoltaics (OPV) also provides attractive properties like flexibility, colorful displays and transparency which could open new market opportunities. The material and device innovations lead to improved efficiency by 8% for organic photovoltaic solar cells, compared to 4% in 2005. Both academic and industry research have significant interest in the development of this technology. This book gives an overview of the booming technology, focusing on the solution process for organic solar cells and provides a state-of-the-art report of the latest developments. World class experts cover fundamental, materials, devices and manufacturing technology of OPV technology.
Download or read book Organic Photovoltaics written by Christoph Joseph Brabec and published by Springer Science & Business Media. This book was released on 2013-11-21 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present volume describes and explains the fundamentals of organic/plastic solar cells in a manner accessible to both researchers and students. It provides an up-to-date and comprehensive account of these materials and corresponding devices, which will play a key role in future solar energy systems.
