DFT improving the optoelectronic and thermoelectric performance of Ba2SrXO6(X = Cr, Mo, W) for solar cell applications

Abstract

In this work, We investigated stability, electronic, optical, and thermoelectric properties of the double perovskite oxides Ba₂SrXO₆(X = Cr, Mo and W) are investigated using density functional theory (DFT) via the full-potential linearized augmented plane wave (FP-LAPW) method, as implemented in the WIEN2k code. Structural optimization confirms the crystalline stability of all three compounds, supported by Goldschmidt tolerance factors, negative formation enthalpies, and elastic constants that satisfy Born’s stability criteria. Mechanical analysis reveals that Ba₂SrMoO₆ and Ba₂SrWO₆ exhibit ductile behavior, whereas Ba₂SrCrO₆ is more brittle. Electronic band structure calculations using the modified Becke–Johnson (mBJ) potential indicate that all compounds are semiconductors with indirect band gaps. The found band gap for studied materials are $1.005\text{eV}$ for Ba₂SrCrO₆, $3.873\text{eV}$ for Ba₂SrWO₆ and $2.801\text{eV}$ for Ba₂SrMoO₆. The optical properties show strong absorption in the visible range for Ba₂SrCrO₆, while Ba₂SrMoO₆ and Ba₂SrWO₆ demonstrate significant optical activity in the ultraviolet region. The results obtained are supported by the calculated optical conductivity, reflectivity, dielectric function, and refractive index. Finally, thermoelectric calculations using BoltzTraP reveal that these materials particularly Ba₂SrCrO₆ exhibit a increased Seebeck coefficient and a promising figure of merit at high temperatures, highlighting their potential for thermal energy conversion applications, especially in Solar cells and thermoelectric devices.