IIc-1 - Amorphous Silicon Solar Cells

Abstract

This chapter focuses on amorphous silicon solar cells. Significant progress has been made over the last two decades in improving the performance of amorphous silicon (a-Si) based solar cells and in ramping up the commercial production of a-Si photovoltaic (PV) modules, which is currently more than 4:0 peak megawatts (MWp) per year. The progress in a-Si solar cell technology can be attributed to concurrent advances in the areas of new and improved materials, novel cell designs, and in the development of large-area deposition techniques suitable for mass production. Researches on silicon deposited from a silane discharge have shown that it has a much lower density of defects than evaporated or sputtered amorphous silicon. Amorphous silicon has useful optoelectronic properties. Hydrogen plays an important role in determining the optoelectronic properties of these materials, and discharge-deposited a-Si is actually an alloy of hydrogen and silicon, or hydrogenated amorphous silicon (a-Si:H). Large changes in the photoconductivity and dark conductivity of a-Si:H are observed when the material is exposed to sunlight. This chapter discusses amorphous silicon alloys, deposition conditions, and microstructure of amorphous silicon. Physics of operation, device structures, performance and stability, and reliability of amorphous silicon solar cells are also discussed. The chapter also describes the manufacturing process and environmental issues with production of amorphous silicon solar cells.