The highest photovoltaic conversion efficiency of single-crystal silicon solar cells reaches 24%, the highest among all types of solar cells. However, the high production cost of single-crystal silicon solar cells has prevented their widespread and widespread use. Polycrystalline silicon solar cells are cheaper than single-crystal silicon solar cells in terms of production cost, but their photovoltaic conversion efficiency is significantly lower. In addition, their service life is also shorter than that of single-crystal silicon solar cells. Therefore, in terms of performance-price ratio, single-crystal silicon solar cells are slightly better.
Researchers have discovered that some compound semiconductor materials are suitable for thin-film solar photovoltaic conversion. For example, CdS and CdTe; III-V compound semiconductors: GaAs and AlP InP; thin-film solar cells made with these semiconductors exhibit excellent photovoltaic conversion efficiency. Semiconductor materials with gradient band gaps (the energy difference between the conduction band and the valence band) can expand the solar absorption spectrum, thereby improving photovoltaic conversion efficiency. This presents broad prospects for the widespread practical application of thin-film solar cells. Among these multi-element semiconductor materials, Cu(In,Ga)Se2 is an excellent solar light absorber. Based on it, thin-film solar cells can be designed with significantly higher photoelectric conversion efficiency than silicon thin-film solar cells, and the photoelectric conversion efficiency that can be achieved is 18%.
