Exploring the electronic and optical properties of vacancy-ordered double perovskites Cs2PtX6 (X = Cl, Br, I)

We have comprehensively investigated the structural stability, mechanical, electronic and optical properties of vacancy-ordered double perovskites Cs2PtX6 (X = Cl, Br, I) through the first-principles calculations in this article. The stability of three compounds are proved by calculating their elastic constants and phonon dispersion. The results suggest that three Pt-based double perovskites are direct bandgap semiconductors. The band gaps of Cs2PtCl6, Cs2PtBr6, and Cs2PtI6 are 3.45, 2.45, and 1.41 eV, respectively. The optical properties of these compounds in the visible light region have been explored by the HSE06 method. The highest optical absorption coefficient of Cs2PtBr6 exceeds 5 x 10(5) cm(-1), and the strong optical absorption of Cs2PtI6 is in the range of 300-600 nm. The excellent physical properties make lead-free Cs2PtI6 suitable for single-junction solar cells.

Automated summary

This study investigated the structural stability, mechanical, electronic and optical properties of vacancy-ordered double perovskites Cs2PtX6 (X = Cl, Br, I) through first-principles calculations. The results show that these compounds are suitable for single-junction solar cells.