DFT study of halogen based double perovskite Na2AgAlX6 (X = Cl, Br, I) double perovskites for energy harvesting applications

Double perovskites halides show a lot of potential for being utilized in energy converting applications. This research offers a comprehensive investigation of photovoltaic features of halogen based double perovskite Na2AgAlX6 (X = Cl, Br, I) through DFT approach including structural, thermoelectric and optoelectronic features. The structural stability of the investigated materials is verified by Born's stability criterion. The ductility of Na2AgAlX6 is confirmed by the Poisson coefficient (upsilon > 0.26) and a Pugh ratio (B/G > 1.75). The bandgap 3.7 eV, 2.7 eV, and 1.3 eV of Na2AgAlX6 (X = Cl, Br, I) has been observed with direct nature. The replacement of Br and I with Cl leads to the lowering of bandgap value due to the closer of band edges. The absorption factor, reflective properties, and dielectric parameters are used to evaluate the optical features. The BoltzTraP software played vital role in calculating the thermoelectric characteristics, such as ZT value, power factor, and their electrical and thermal conductivities. The results of these calculated properties indicate that Na2AgAlX6 (X = Cl, Br, I) double perovskite halides show a promising potential for energy renewable applications.