Optimizing Band Gap of Inorganic Halide Perovskites by Donor-Acceptor Pair Codoping

Inorganic halide perovskites (IHPs) are promising candidates for applications in solar cell devices. However, the band gaps of most IHPs are too large, so that the energy conversion efficiency is limited. In this work, we proposed a donor-acceptor pair codoping scheme to reduce the band gaps Sn- and Pb-based IHPs, based on first-principles calculations. Interestingly, the donor-acceptor pair codoping in CsSnBr₃ and CsPbI₃ can produce band gaps of 1.2 and 1.1 eV, respectively, both of which are close to the optimal band gap for solar cell materials. The absorption coefficient of donor-acceptor pair codoped CsSnBr₃ and CsPbI₃ in the visible light region are large, which indicates that they are good light absorbers for applications in solar cell devices.