The roles of surface defects in MAPbBr3 and multi-structures in MAPbI3

Abstract The research of perovskites optical properties is of great value for dual wavelength lasers. However, the phenomenon of double peaks in perovskites photoluminescence (PL) has not been explained systematically, which makes the optical research of perovskites still a challenge. In order to have a deep understanding of the optical properties and applications of new perovskite materials, this phenomenon of MAPbX3 (X = I−, Br−) is explained in this paper. The structural characteristics of the materials were investigated by XRD. We found that there were PbBr2 defects in MAPbBr3 and orthorhombic structure defects in MAPbI3; By calculating the energy level distribution of perovskites and defects, the PbBr2 in MAPbBr3 and orthorhombic phase structure in MAPbI3 can introduce a new energy level into crystals and these two structures lead to the PL peaks of 542 nm and 771 nm, respectively. It is the surface defects in MAPbBr3 and multi-structures in MAPbI3 that leads to the two peaks phenomenon of perovskite photoluminescence. All the work explained the mechanism of perovskites PL double peaks. This study can provide theoretical reference for perovskites researches and experimental references for new materials and a promising pathway for dual-wavelength, practical laser based on perovskite crystals.