A New Lead Free Double Perovskites K2Ti(Cl/Br)6 for renewable energy; Probed by DFT

Abstract Double perovskites are outstanding materials for optoelectronic and renewable energy applications. In the present study, we explored the optical and thermoelectric properties of K2Ti (Cl/Br)6 by Wien2k and BoltzTraP codes. Thermodynamic and structural stabilities are confirmed by tolerance factor (0.98, 0.99) and negative formation energy. We found a direct band gap of 2.80 eV for K2TiCl6 and 2.1 eV for K2TiBr6. The maximum absorption region from visible to ultraviolet region (2.5 eV to 4 eV) suggest them suitable for solar cells. Moreover, polarization and dispersion of light are explained in terms of dielectric constant and refractive index, respectively. Thermoelectric properties are elaborated with electrical conductivity, Seebeck coefficient, and figure of merit.