The study of optical and thermoelectric behaviour of thalium based flouropervoskite (TlSiF3) for photovoltaic and renewable energy applications by DFT

Abstract

In the present study, structural, electronic, optical, thermodynamic and thermoelectric properties of perovskites TlSiF3 are explored using first-principles calculations based on density functional theory with different exchange-correlation approximations (LDA, PBE-GGA, WC-GGA, PBE-sol GGA, and mBJ-GGA). The computed structure, electronic and charge density plots using PBE-GGA ​+ ​TB-mBJ approximation show that TlSiF3 is an indirect band gap semiconductor (1.73 ​eV gap along with R– M direction) having ionic and covalent bonding. The optical response is analysed and explained in terms of dielectric function, refractive index, extinction coefficient, optical conductivity, reflectivity, and absorption coefficient in the energy range from 0 to 10 ​eV. The thermoelectric transport behaviour of TlSiF3is computed as a function of temperature and chemical potential, μ−EF. Further, the thermoelectric transport behavior of TlSiF3 is computed as a function of temperature and chemical potential μ−EF (eV). It has been observed that highest value of ZT (0.43) is attained at 1000 ​K with a power factor (PF) of 9.3 ​× ​1010WK−2m−1s−1for a fixed chemical potential. Under varying chemical potential at 300K in n-type region, it exhibits ZT value of 0.98, which is required for thermoelectric devices. Furthermore, pressure as well as temperature dependence of the thermodynamic parameters like Debye temperature, heat capacity, bulk modulus, thermal expansion coefficient, heat capacity, have been estimated with the help of GIBBS program based on quasi-harmonic Debye model.