Energy Conversion Efficiency of Solar Cells

ISBN-13: 9789811390913 / Angielski / Miękka / 2020 / 202 str.

Takashi Kita; Yukihiro Harada; Shigeo Asahi

Spis treści

1. The solar cell and the electrochemical cell

1.1 Principle of electricity generation in an electrochemical cell

1.2 Principle of electricity generation in a solar cell

1.3 Comparison between electrochemical cell and solar cell

2. Photons from the Sun

2.1 The wavelength of light and its energy

2.2 The wavelengths of sunlight

2.3 Black-body radiation

2.4 Definition of the solid angle

2.5 The photon flux from a black body

3. “Graphical solution” for the solar cell conversion efficiency in the completely ideal case

3.1 The conversion efficiency of a solar cell

3.2 The semiconductor band gap

3.3 Transmission and thermalization losses caused by the band gap

3.4 Definition of the ideal solar cell conditions

3.5 The three-dimensional visualization of the solar cell’s output power

3.6 The derivation of the solar cell conversion efficiency curve for the completely ideal case

4. Influences of carrier generation and recombination on the solar cell conversion efficiency

4.1 The solar cell’s energy input

4.2 The relation between electrical current and voltage

4.3 Short-circuit current and open-circuit voltage

5. The conversion efficiency of a solar cell as determined by the detailed balance model

5.1 The nominal efficiency

5.2 The detailed balance limit of the conversion efficiency

5.3 Losses in solar cells

6. Actual calculation of solar cell efficiencies

6.1 Single-junction solar cell

6.2 Concentrator solar cell

6.3 Multi-junction solar cell

6.4 Intermediate-band solar cell

6.5 Two-step photon up-conversion solar cell

6.6 Solar cells with spectral converters

6.7 Influence of the weather

6.8 Influence of the temperature

6.9 Indoor photovoltaic cell

7. Application limits for the ideal conditions

7.1 Consideration of the absorption coefficient

7.2 The minority-carrier diffusion

7.3 Photocurrent densities calculated for different materials under consideration of the layer thickness

8. Fundamentals of semiconductors

8.1 The semiconductor band gap

8.2 The intrinsic semiconductor

8.3 The extrinsic semiconductor

8.4 Energy levels of impurities and carrier generation

8.5 The carrier distribution within a band

8.6 The Fermi level

8.7 Temperature dependence of the carrier density

8.8 The currents in a semiconductor: drift current and diffusion current

8.9 The quasi-Fermi level

8.10 The p–n junction

8.11 Current–voltage characteristics of a p–n junction

O autorze

Takashi Kita is a Professor at Kobe University. He received his Doctor of Engineering degree from Osaka University in 1991. In 1990 he was appointed as Assistant Professor at Kobe University, and promoted to Associate Professor and his current position in 2000 and 2007, respectively. In 1996, he worked as a Visiting Researcher in the group led by Professor Hans-Joachim Queisser, Max-Plank Institute. His work is mainly concerned with the development of high-performance photonic devices, and has been recognized with the Japan Society of Applied Physics Fellow Award.

Yukihiro Harada is an Assistant Professor at Kobe University, where he received his Doctor of Engineering degree in 2009 and was appointed to his current position the same year. From 2016 to 2017, he worked as a Visiting Researcher in the group led by Dr. Nicholas J. Ekins-Daukes, Imperial College London, UK. His work is mainly concerned with the optical properties of semiconductor nanostructures. He is a member of the Japan Society of Applied Physics, the Physical Society of Japan, and the Optical Society of America.

Shigeo Asahi is a Project Assistant Professor at Kobe University. He received his Master of Engineering degree from the University of Tokyo in 2003. After working for a private company for ten years, he enrolled at Kobe University in 2013 and completed his PhD in 2016. He was appointed to his current position the same year. His work is mainly concerned with the development of high-efficiency solar cells.

Blurb

This book offers a concise primer on energy conversion efficiency and the Shockley-Queisser limit in single p-n junction solar cells. It covers all the important fundamental physics necessary to understand the conversion efficiency, which is indispensable in studying, investigating, analyzing, and designing solar cells in practice. As such it is valuable as a supplementary text for courses on photovoltaics, and bridges the gap between advanced topics in solar cell device engineering and the fundamental physics covered in undergraduate courses.

The book first introduces the principles and features of solar cells compared to those of chemical batteries, and reviews photons, statistics and radiation as the physics of the source energy. Based on these foundations, it clarifies the conversion efficiency of a single p-n junction solar cell and discusses the Shockley-Queisser limit. Furthermore, it looks into various concepts of solar cells for breaking through the efficiency limit given in the single junction solar cell and presents feasible theoretical predictions. To round out readers’ knowledge of p-n junctions, the final chapter also reviews the essential semiconductor physics.

The foundation of solar cell physics and engineering provided here is a valuable resource for readers with no background in solar cells, such as upper undergraduate and master students. At the same time, the deep insights provided allow readers to step seamlessly into other advanced books and their own research topics.