Electronic structure of organometal halide perovskite CH3NH3BiI3 and optical absorption extending to infrared region

摘要

The electronic structure and optical absorption spectrum of organometal halide perovskite compound CH3NH3BiI3 as a substituting candidate of well-concerned CH3NH3PbI3 not only for environmental friendly consideration are studied using the first principles calculations. It is revealed that a Bi replacement of Pb in CH3NH3PbI3 does not change seriously the band edge structure but the bandgap becomes narrow. Consequently, CH3NH3BiI3 exhibits not only stronger visible light absorption than CH3NH3PbI3 does but more strong absorption in the infrared region, which is however absent in CH3NH₃PbI₃. It is suggested that CH₃NH₃BiI₃ may be one of even more promising alternatives to CH₃NH₃PbI₃ for spectrum-broad and highly-efficient solar cells.