Electronic structure of organometal halide perovskite CH(3)NH(3)BiI(3) and optical absorption extending to infrared region

The electronic structure and optical absorption spectrum of organometal halide perovskite compound CH(3)NH(3)BiI(3) as a substituting candidate of well-concerned CH(3)NH(3)PbI(3) not only for environmental friendly consideration are studied using the first principles calculations. It is revealed that a Bi replacement of Pb in CH(3)NH(3)PbI(3) does not change seriously the band edge structure but the bandgap becomes narrow. Consequently, CH(3)NH(3)BiI(3) exhibits not only stronger visible light absorption than CH(3)NH(3)PbI(3) does but more strong absorption in the infrared region, which is however absent in CH(3)NH(3)PbI(3). It is suggested that CH(3)NH(3)BiI(3) may be one of even more promising alternatives to CH(3)NH(3)PbI(3) for spectrum-broad and highly-efficient solar cells.