Abstract
Pressure-dependent elasto-mechanical, thermoelectric and thermodynamic properties of two direct band gap halide perovskites MYbF3 (M = Rb, Cs) have been investigated using density functional theory calculations. These calculations were carried out within Wein2k simulation code aided by generalized gradient approximation, Charpin method, BoltzTrap package and quasi-harmonic Debye model. The computed elastic constants (C-11, C-12 and C-44) are all positive and follow the mechanical stability criteria within the applied pressure range (0-15 GPa). The obtained mechanical properties show that both the compounds are stiffer and oppose changes in the shape and volume up to a great extent. Moreover, MYbF3 compounds are ductile and bonded with central forces whereas exhibiting unique properties in different crystallographic positions as shown by Zener anisotropic factor values. Thermoelectric parameters in the temperature range 200 to 800 K suggest these compounds for commercial thermoelectric device engineering due to low thermal conductivity, high electronic conductivity and moderate values of the figure of merit. The overall effect of thermodynamic parameters shows these compounds can withstand high temperature and pressure. The calculations specified these materials ideal for renewable energy generation.