This book focuses on organic semiconductors with particular attention paid to their use as photovoltaic devices. It addresses a fundamental and hitherto overlooked concept in the field of organic optoelectronics, namely the role that sub-gap states play in the performance of organic semiconducting devices. From a technological point of view, organic semiconductor-based devices are of significant interest due to their lightweight, ease of processability, conformal flexibility, and potentially low cost and low embodied energy production. Motivated by these rather unique selling points, the performance of organic semiconductors has been a subject of multidisciplinary study for more than 60 years with steady progress in applications such as solar cells, transistors, light emitting diodes, and various sensors.
The book begins with a review of the main electro-optical phenomena in organic solar cells and presents a new method for measuring exciton diffusion lengths based on a low-quencher-content device structure. Furthermore, the book reveals how mid-gap trap states are a universal feature in organic semiconductor donoracceptor blends, unexpectedly contributing to charge generation and recombination, and having profound impact on the thermodynamic limit of organic photovoltaic devices. Featuring cutting-edge experimental observations supported with robust and novel theoretical arguments, this book delivers important new insight as to the underlying dynamics of exciton generation and diffusion, charge transfer state dissociation, and indeed the ultimate fate of photogenerated free carriers.

Explores the optoelectronic properties of organic semiconductors relevant for new photovoltaic devices Features a set of impressive experimental results supported by a strong and novel theoretical argument Describes a well-defined research problem and closes with a set of self-contained conclusions

Autorentext

Dr. Nasim Zarrabi was born and raised in Qazvin, Iran. She has pursued her passion for science in three countries. After completing her undergraduate studies in physics in Iran, she relocated first to Germany and then to Australia in 2015. She was introduced to organic electronics and began her research carrier in this field when she joined the Centre for Organic Photonics and Electronics (COPE) at the University of Queensland as a research assistant. In 2017, she moved to the UK to become part of the Sêr SAM research team in Swansea as a Ph.D. candidate. In May 2021, she completed her Ph.D. in Physics under the supervision of Dr. Ardalan Armin and Professor Paul Meredith at Swansea University. Her Ph.D. research was focused on the optical and electronic processes in disorder semiconductors, specifically, organic semiconductor devices. Dr. Zarrabi is currently a postdoctoral research associate at Swansea University, analyzing the fundamental limits of organic optoelectronic devices such as photodetectors and solar cells.

Inhalt

Introduction.- Electro-Optical Phenomena in Organic Solar Cells.- Anomalous Exciton Quenching in Organic Semiconductors.- On the Eect of Mid-gap Trap States on the Thermodynamic Limit of OPV Devices.- Relating Charge Transfer State Kinetics and Strongly Reduced Bimolecular Recombination in Organic Solar Cells.