Design of (C3N2H5)(1-)Cs PbI3 as a novel hybrid perovskite with strong stability and excellent photoelectric performance: A theoretical prediction

Due to its unique properties, such as long carrier diffusion length and adjustable optical band gap, organic-inorganic hybrid perovskite has been a potentially strong photoelectric material for solar cells. However, the challenge of insufficient stability of perovskite materials has not been solved, which in turn, limits its commercial application. Inspired by the strong stability of C3N2H5PbI3 (ImPbI3), we present an innovative doped system, Im(1-x)CsxPbI3 (x = 0.25, 0.5, 0.75), based on the cation-doped strategy, to obtain both strong stability and excellent photoelectric performance. A new perovskite phase ImPbI3 is proposed and verified rationality of existence through formation energy, ab initio molecular dynamics (AIMD), mean square displacement (MSD), and X-ray diffraction (XRD) based on density functional theory (DFT) calculations. For analyzing the photoelectric properties of Im(1-x)CsxPbI3, the bandgap, charge distribution of the frontier molecular orbital, and projected density of states are investigated. To study the stability of Im(1-x)CsxPbI3, geometric configuration, tolerance factor, crystal orbital Hamilton populations (COHP), and AIMD simulations are performed. The results show that the perovskite phase ImPbI3 has strong thermodynamic stability and structural stability, and its optical bandgap value is lower than that of the hexagonal system. When the content of doped Cs does not exceed 50%, the stability of the perovskite phase ImPbI3 is significantly improved. Comprehensive analysis shows that Im0.5Cs0.5PbI3 exhibits encouraging performance with strong stability and high optical absorption coefficient. This theoretical study opens a new avenue for the design of robust organic-inorganic hybrid perovskite materials with strong stability and excellent photoelectric performance based on our findings from perovskite phase ImPbI3 system.