Tuning of band gap by variation of halide ions in K2CuSbX6 (X = Cl, Br, I) for solar cells and thermoelectric applications

The double perovskites have obtained remarkable attention in the field of solar cells and renewable energy applications. Here in present article, the optical and transport properties of K2CuSbX6 (X = Cl, Br, I) are illustrated by DFT based simulation WIEN2K codes. The formation energy has been calculated for thermodynamic stability. The indirect band gaps (1.12, 0.80, and 0.43) for (Cl, Br, I) studied DPs halides are reported from band structures which instigate diverse optoelectronic and transport applications. The width of absorption band increases from Cl to I and shifted towards to lower frequency region. Furthermore, thermoelectric parameters are evaluated in the temperature range 200–600K and chemical potential ±0.15 eV. The ultralow values of lattice conductivity and large ZT at 300K increases their significant importance for thermoelectric generators and renewable energy devices. •Double perovskites are more stable, cheap, and suitable materials for solar cells.•The large value of efficiency of conversion light energy into electrical energy.•The absorption bands of light energy exist visible to infrared region.•The large figure of merit at room temperature and ultralow lattice thermal conductivity.