Investigation of self-doping in perovskites with vacancy defects based on first principles

In order to obtain excellent perovskite materials, we systematically investigate the structural, electronic and optical properties of perovskites and the influence of vacancy defects on their optical properties. First, we explore the structural properties of intrinsic perovskites via Materials Studio and use the Generalized Gradient Approximation(GGA) with the Perdew-Burke-Ernzerhof(PBE) function to optimize the crystal structure and calculate the electronic or optical properties. To obtain accurate bandgap, we use Density Functional Theory-Vander Waals Force(DFT-VDW) correlations to explain the underestimated bandgap. The investigations of the different vacancy defects in perovskites are then carried out and the band structure, density of states and optical properties are measured. Finally, the properties of self-doped perovskites with vacancy defects are further investigated with comparison to the properties of intrinsic perovskites. Our results indicate that the obtained bandgap of intrinsic perovskites was 1.52 eV, which is consistent with the experimental value. The perovskites with Pb vacancy defects belong to P-type materials and those with I vacancy defects belong to N-type materials. The dielectric virtual function and absorption spectrum exhibit substantial change, which has important theoretical value for the physical properties of perovskites and their applications in the fields of optoelectronic devices.