Phonon anharmonicity in lead-halide perovskites: CsPbBr₃

Using ab initio molecular dynamics we demonstrate that a highly anharmonic nature of atomic motions in CsPbBr₃ is responsible for its unusual temperature of charge carrier lifetime. As temperature increases, vibrational spectra of perovskite structure demonstrate a noticeable shift in frequency and anharmonic atomic motion is observed. We calculated Gru¨neisen parameter as function of pressure. We analyze the thermal expansion of CsPbBr₃, discuss multi-phonon processes, phonon coupling and decay pathways. The results are compared with the available experimental Raman spectroscopy.