Overview and Perspective for High-Efficiency Single-Junction Solar Cells

Photovoltaic energy conversion is expected to contribute to creation of a clean energy society and high-performance solar cells are very attractive for realizing such a vision. The development of high-performance solar cells offers a promising pathway toward achieving high power per unit cost for many applications. Although state of the art of some of single-junction solar cells are approaching the Shockley-Queisser limit of 32-33%, further improvements in efficiencies of solar cell and modules are thought to be possible. Herein, efficiency improvements in various single-junction solar cells are overviewed in this article and several losses of high-efficiency single-junction solar cells are discussed about. Perspective of single-junction solar cells from the viewpoint of practically feasible efficiency based on scientific and technological arguments is also presented. In addition, problems to be solved for solar cell modules are discussed.