Theoretical investigation of the structural stability, electronic and optical properties of the double perovskite Cs2ZrX6 (X=Cl, Br, I)

In recent years, in order to solve the energy issue researchers have performed much investigations, among which inorganic metal halide chalcogenides have received extensive attention in the field of materials, energy and other fields for their excellent photovoltaic properties. However, the traditional halide chalcogenide has two deadly deficiencies, poor thermal stability and the presence of toxic lead elements, which prevent its applications. Compared with ABX3-type halide chalcogenides, double lead-free perovskites usually have the advantages of better thermal stability and less toxicity, which makes it easier to be commercialized. In addition, elemental substitution methods can be employed to modulate their energy bands and optical properties. Here, the structural stability, electronic and optical properties, and thermodynamic properties of cesium zirconium halide double perovskites Cs2ZrX6 (X = Cl, Br, I) are systematically investigated based on density functional theory (DFT) to predict their applications in the photovoltaic and optoelectronic industries. The computational results show that these cesium zirconium halide double perovskites have very good structural stability as well as special optical properties such as strong light absorption, large dielectric constant, and low reflectivity. Moreover, all of them belong to direct bandgap semiconductors and possess small effective masses, which indicates that the double perovskites could be potential candidates for future optoelectronic devices and applications.