The photoelectric conversion efficiency of monocrystalline silicon solar energy is up to 24%, which is the highest photoelectric conversion efficiency among all types of solar cells. But monocrystalline silicon solar cells are so expensive to make that they are not yet widely and universally used in large numbers. Polycrystalline silicon solar cells are cheaper than monocrystalline silicon solar cells in terms of production cost, but the photoelectric conversion efficiency of polycrystalline silicon solar cells is much lower. In addition, the service life of polycrystalline silicon solar cells is also shorter than that of monocrystalline silicon solar cells. Therefore, in terms of cost performance, monocrystalline silicon solar cells are slightly better.

Researchers have found that some compound semiconductor materials are suitable for solar photoelectric conversion films. For example, CdS, CdTe; III-V compound semiconductors: GaAs, AIPInP, etc.; thin film solar cells made of these semiconductors show good photoelectric conversion efficiency. Semiconductor materials with multiple gradient energy band gaps can expand the spectral range of solar energy absorption, thereby improving the photoelectric conversion efficiency. So that a large number of practical applications of thin-film solar cells show broad prospects. Among these multi-component semiconductor materials, Cu(In,Ga)Se2 is an excellent solar light absorbing material. Based on it, thin-film solar cells with significantly higher photoelectric conversion efficiency than silicon can be designed, and the photoelectric conversion rate that can be achieved is 18%.