Organic Photovoltaics

Recently developed organic photovoltaics (OPVs) show distinct advantages over their inorganic counterparts due to their lighter weight, flexible shape, versatile materials synthesis and device fabrication schemes, and low cost in large-scale industrial production. Although many books currently exist on general concepts of PV and inorganic PV materials and devices, few are available that offer a comprehensive overview of recently fast developing organic and polymeric PV materials and devices. Organic Photovoltaics: Mechanisms, Materials, and Devices fills this gap. The book provides an international perspective on the latest research in this rapidly expanding field with contributions from top experts around the world. It presents a unified approach comprising three sections: General Overviews; Mechanisms and Modeling; and Materials and Devices. Discussions include sunlight capture, exciton diffusion and dissociation, interface properties, charge recombination and migration, and a variety of currently developing OPV materials/devices. The book also includes two forewords: one by Nobel Laureate Dr. Alan J. Heeger, and the other by Drs. Aloysius Hepp and Sheila Bailey of NASA Glenn Research Center. Organic Photovoltaics equips students, researchers, and engineers with knowledge of the mechanisms, materials, devices, and applications of OPVs necessary to develop cheaper, lighter, and cleaner renewable energy throughout the coming decades.

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.

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 electron donor and acceptor materials. Design, preparation, and evaluation of these materials targeting highest performance are discussed. This includes contributions on modeling down to the molecular level to device-level electrical and optical testing and modeling, as well as layer morphology control and characterization. The integration of the different components in device architectures suitable for mass production is described. Finally, the technical feasibility and economic viability of large-scale manufacturing using fast inexpensive roll-to-roll deposition technologies is assessed.

This book reports on the design, synthesis and characterization of new small molecule electron acceptors for polymer solar cells. Starting with a detailed introduction to the science behind polymer solar cells, the author then goes on to review the challenges and advances made in developing non-fullerene acceptors so far. In the main body of the book, the author describes the design principles and synthetic strategy for a new family of acceptors, including detailed synthetic procedures and molecular modeling data used to predict physical properties. An indepth characterization of the photovoltaic performance, with transient absorption spectroscopy (TAS), photo-induced charge extraction, and grazing incidence X-ray diffraction (GIXRD) is also included, and the author uses this data to relate material properties and device performance. This book provides a useful overview for researchers beginning a project in this or related areas.

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.

The last two decades have seen unprecedented research progress made in the fabrication and testing of organic solar cell (OSC) devices due to, among other things, rapid growth of interest in the development of organic materials for photovoltaic applications, the ease of processing, and the prospect of achieving high power conversion efficiency (PCE) cost effectively. The effects of impurity doping at the ppm level in photovoltaic organic semiconductors, including: (i) Seven-nines purification of organic semiconductors, (ii) pn-control of single and co-deposited organic semiconductors by impurity doping, (iii) ionisation sensitisation of doping showing the doping efficiency of 100%, (iv) ppm-doping effects in the simplest n+p-homojunction organic photovoltaic cells, and (v) the Hall effect of bulk-doped organic single crystals, are discussed in Chapter One. In Chapter Two the fabrication and characterisation of perovskite-type solar cells are reviewed and summarised such as CH3NH3PbI3, [HC(NH2)2]PbI3, and CsSnI3, which are expected for solar cell materials. Chapter Three proposes an experimental method to tailor SDE and optimise the power conversion efficiency (PCE), based on the electrical transport curve. Chapter Four provides a brief history of organic photovoltaic cell devices, factors limiting stability and power conversion efficiency, fundamental parameters that have been reported to improve the general performance of the devices, and recent developments in organic solar cell devices.

This book covers in a textbook-like fashion the basics or organic solar cells, addressing the limits of photovoltaic energy conversion and giving a well-illustrated introduction to molecular electronics with focus on the working principle and characterization of organic solar cells. Further chapters based on the author’s dissertation focus on the electrical processes in organic solar cells by presenting a detailed drift-diffusion approach to describe exciton separation and charge-carrier transport and extraction. The results, although elaborated on small-molecule solar cells and with focus on the zinc phthalocyanine: C60 material system, are of general nature. They propose and demonstrate experimental approaches for getting a deeper understanding of the dominating processes in amorphous thin-film based solar cells in general. The main focus is on the interpretation of the current-voltage characteristics (J-V curve). This very standard measurement technique for a solar cell reflects the electrical processes in the device. Comparing experimental to simulation data, the author discusses the reasons for S-Shaped J-V curves, the role of charge carrier mobilities and energy barriers at interfaces, the dominating recombination mechanisms, the charge carrier generation profile, and other efficiency-limiting processes in organic solar cells. The book concludes with an illustrative guideline on how to identify reasons for changes in the J-V curve. This book is a suitable introduction for students in engineering, physics, material science, and chemistry starting in the field of organic or hybrid thin-film photovoltaics. It is just as valuable for professionals and experimentalists who analyze solar cell devices.

Providing complementary viewpoints from academia as well as technology companies, this book covers the three most important aspects of successful device design: materials, device physics, and manufacturing technologies. It also offers an insight into commercialization concerns, such as packaging technologies, system integration, reel-to-reel large scale manufacturing issues and production costs. With an introduction by Nobel Laureate Alan Heeger.