Revealing the remarkably improved structural, phonon, elastic, optoelectronic and thermoelectric properties of TlXF3(X [formula omitted] Ca, Cd) for energy applications using first-principles approach with hybrid and range-separated hybrid functionals

Abstract

This study reports the first-principles investigations of flouroperovskites, TlXF3(X = Ca, Cd), within the frame work of Density Functional Theory. A comprehensive and improved data of flouroperovskites on structural, phonon, elasto-mechanical, optoelectronic and thermoelectric properties are carried out using Perdew Burke Ernzerhof-Generalized Gradient Approximation (PBE-GGA), Trans-Blaha modified Becke–Johnson (TB-mBJ), meta GGA, Strongly Constrained and Appropriately Normed (SCAN), hybrid functional including Becke’s three parameter exchange functional with the Lee–Yang–Parr (B3LYP) and range-separated hybrid functional Heyd–Scuseria–Ernzerhof (HSE06). The structures are optimized and stability is proved by energy-volume optimization, formation energy calculations, positive phonon frequencies of phonon dispersion curves and elastic constant criteria. The electronic band structures of both TlCaF3 and TlCdF3 possess direct and indirect nature respectively and density of states are consistent with electronic band structure. The band gaps of TlCaF3 are 4.53 eV (PBE-GGA), 6.19 eV (TB-mBJ), 4.89 eV (SCAN), 6.24 eV (B3LYP) and 5.98 eV (HSE06) and the band gaps of TlCdF3 are 3.74 eV (PBE-GGA), 5.64 eV (TB-mBJ), 4.30 eV (SCAN), 5.83 eV (B3LYP) and 5.53 eV (HSE06). The dynamical stability and brittle response of TlCaF3 and TlCdF3 is confirmed from shear constant, Pugh’s ratio and Poisson’s ratio. The optical and thermoelectric response are studied for optoelectronic and sustainable applications.