Reducing lead toxicity in the methylammonium lead halide MAPbI(3): Why Sn substitution should be preferred to Pb vacancy for optimum solar cell efficiency

摘要

Methylammonium lead halide (MAPbI(3)) perovskite has emerged as one of the frontier optoelectronic semiconductors. To avoid lead toxicity, the role of Sn substitution and Pb vacancy (Pb-boxed times) are addressed in regulating stability and solar cell efficiency of MAPb(1-X-Y)Sn(X) boxed times(Y) I-3 perovskite using hybrid density functional theory (DFT). The role of spin-orbit coupling (SOC) and the electron's self-interaction error are examined carefully. We find to reduce the Pb content from pristine MAPbI(3), Sn substitution has a more favorable thermodynamic stability than creating Pb-boxed times. Moreover, on substituting Sn, due to strong s-p and p-p couplings, the lower parts of the conduction band gets shifted downwards, which results in the reduction of the band gap (direct). This further helps us to get a high optical absorption coefficient (redshifted) and maximum solar cell efficiency in MAPb(1-X)Sn(X)I(3) for 0 < X <= 0.5.