Temperature-Induced Large Broadening and Blue Shift in the Electronic Band Structure and Optical Absorption of Methylammonium Lead Iodide Perovskite

The power conversion efficiency of hybrid halide perovskite solar cells is profoundly influenced by the operating temperature. Here we investigate the temperature influence on the electronic band structure and optical absorption of cubic CH3NH3PbI3 from first-principles by accounting for both the electron-phonon interaction and thermal expansion. Within the framework of density functional perturbation theory, the electron-phonon coupling induces slightly enlarged band gap and strongly broadened electronic relaxation time as temperature increases. The large broadening effect is mainly due to the presence of cation organic atoms. Consequently, the temperature-dependent absorption peak exhibits blue-shift position, decreased amplitude, and broadened width. This work uncovers the atomistic origin of temperature influence on the optical absorption of cubic CH3NH3PbI3 and can provide guidance to design high-performance hybrid halide perovskite solar cells at different operating temperatures.