Thermoelectric Property Analysis of CsSnX3 Materials (X = I, Br, Cl)

The thermoelectric properties of CsSnI3 are analysed with the ab initio first-principle density functional theory (DFT). Seebeck coefficient, electrical and thermal conductivities are calculated in order to determine the dimensionless figure of merit ZT. Knowing that CsSnI3 is one of the perovskite series of materials that undergo complex phase transitions with temperature, the calculations are performed for different common phases. Several phases of CsSnBr3 and CsSnCl3 are also analysed as comparisons. For the same material, comparison of band structures showed that the band gap increases with phase transition from phase - alpha to phase - beta then to phase - gamma And the ZT values show the same trend as the band gaps. CsSnCl3 exhibits a higher ZT value than CsSnBr3 and CsSnI3 at phase-alpha.