Studies on the Light-Induced Phase Transition of CsPbBr₃ Metal Halide Perovskite Materials

Abstract

We investigate the internal mechanism of the light-induced phase transition of CsPbBr3 perovskite materials via density functional theory simulations. Although CsPbBr3 tends to appear in the orthorhombic structure, it can be changed easily by external stimulus. We find that the transition of photogenerated carriers plays the decisive role in this process. When the photogenerated carriers transit from the valence band maximum to conduction band minimum in the reciprocal space, they actually transit from Br ions to Pb ions in the real space, which are taken away by the Br atoms with higher electronegativity from Pb atoms during the initial formation of the CsPbBr3 lattice. The reverse transition of valence electrons leads to the weakening of bond strength, which is proved by our calculated Bader charge, electron localization function, and integral value of COHP results. This charge transition releases the distortion of the Pb–Br octahedral framework and expands the CsPbBr3 lattice, providing possibilities to the phase transition from the orthorhombic structure to tetragonal structure. This phase transition is a self-accelerating positive feedback process, increasing the light absorption efficiency of the CsPbBr3 material, which is of great significance for the widespread promotion and application of the photostriction effect. Our results are helpful to understand the performance of CsPbBr3 perovskite under a light irradiation environment.

Investigation on the phase transition, geometric and electronic properties of Bi-doped CsPbBr3 perovskites

“…Figures 1 and 2, and figure S1 provide visual representations of the geometric configurations and octahedra for both the orthorhombic and tetragonal CsPbBr 3 . The lattice parameters of the relaxed CsPbBr 3 structures, as presented in table 1, align well with previously reported findings [30][31][32][33].…”