A first-principle study of the structural, mechanical, electronic and optical properties of vacancy-ordered double perovskite Cs2TeX6 (X = Cl, Br, I)

In this work, the structural stability, mechanical, electronic and optical properties of vacancy-ordered double perovskites Cs2TeX6 (X = Cl, Br, I) were investigated by using first-principles calculations. Our calculated results show that these perovskite materials exhibit good structural stability. The calculated direct band gaps of Cs2TeI6 and Cs2TeBr6 agree well with their experimental values. A strong absorption spectrum is observed for Cs2TeI6 in the visible light region. Therefore, we propose Cs2TeI6 as a potential candidate for perovskite solar cells. Moreover, the mechanical properties of Cs2TeX6 were studied for the first time, and the results show that these compounds are ductile materials.