Effect of Cu doping on structural, electronic and thermoelectric properties of double perovskite Cs2NaVCl6

Double halide perovskite constitutes an interesting class of eco-friendly, and stable materials with significant potential as efficient energy harvesting materials. Their simple crystalline packing and tunability offers substantial advantage. Herein, the structural, electronic, and thermoelectric attributes of percentage Cu doped double perovskite (Cs2NaVCl6) is explored with the quantum espresso code within the framework of density functional theory using the generalized gradient approximation (GGA-PBE) with ultra-soft pseudopotential for the inherent atoms. Electronic and thermoelectric properties were all achieved via the GGA + U method to accurately compute the band gap and similar properties. The results express an inverse relationship between the lattice parameters and band gap. The lattice parameters increased with the increase in doping percentage. Similarly, the conductivity of the studied perovskite increased considerably with the increase in the percentage dopant. The calculated band gap was observed within the range of 1.7 eV–1.2 eV decreasing considerably with the increase in percentage doping and therefore suggesting an increase in the conductivity and other thermoelectric properties of the engineered perovskite material. However, the equilibrium lattice constants in accordance with the percentage doping reveal that the higher the percentage doping, the higher the equilibrium lattice constant. This inferred that 25% endohedral replacements of vanadium atoms by copper atoms give the best perovskite material owing to the fact that when the lattice constant increases with a corresponding decrease in the value of modulus of elasticity, there is a decrease in the stability of the perovskite material.