Lattice dynamics of double perovskite Cs2SnCl6 from first principles and experimental studies

[Display omitted] •The Cs2SnCl6 double perovskites were synthesized by the simple hydrothermal method.•Phonon dynamics were investigated using first-principles combined micro-Raman scattering.•Three active modes are originated from Raman symmetry modes (A1g + Eg + 1T2g).•Electronic transitions may be coupled to lattice vibrations, revealing to large Stokes shift energy. The electronic properties and phonon dynamics of Cs2SnCl6 double perovskites have been investigated using first-principles calculations combined micro-Raman scattering and optical spectroscopy. The bandgap of Cs2SnCl6 was found to be about 3.55 eV. The Cl-Sn-Cl stretching modes are ascribed to the Raman peaks at 229.3 and 306 cm−1, respectively, whereas the T2g mode of the Cs+ ions is assigned to the peak at 164 cm−1. All of these findings are consistent with our experiment, indicating that the principal Raman peaks and fundamental vibrational modes are perfectly aligned. Our results provide useful information for basic research of Cs2SnCl6 and its practical applications, such as lead-free double perovskites in emerging nanoelectronics.