A comparative study of structural, electronic and optical properties based on metal-doped methylammonium lead halides via first-principles calculations

Abstract

To reduce the toxicity of Pb in perovskite solar cells, the structural stabilities, electronic and optical properties of the mixed perovskites MAPb_0.75B_0.25I₃ (B = Mg, Ca, Sr, and Ba) were predicted using density functional theory. The calculated results show that the introduction of alkaline-earth metal components caused the structural stabilities of the mixed perovskites to weaken compared to that of MAPbI₃. Moreover, the bandgaps of metal-doped perovskites are larger than that of MAPbI₃. The results indicate that the bandgaps of the mixed perovskites are mainly determined by the Pb–I–B bond angles in the ab plane. The optical absorption coefficients of all of the metal-doped perovskites significantly decrease due to the use of alkaline-earth metals. These results provide a deep insight into a new kind of lead-free perovskite.