Insights on electronic structures, elastic features and optical properties of mixed-valence double perovskites Cs2Au2X6 (X=F, Cl, Br, I)

• Published in: Physics letters. A 2020-03, Vol.384 (8), p.126169, Article 126169
• Main Authors: Du, Xue, He, Dafang, Mei, Huayue, Zhong, Yuhan, Cheng, Nanpu
• Format: Article
• Language: English
• Subjects: Cs2Au2X6; Density function theory; Elastic features; Electronic structures; Mixed-valence double perovskites; Optical properties
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/j.physleta.2019.126169

•Crystal structures and physical properties of Cs2Au2X6 were figured out.•[AuX2]− and [AuX4]− clusters dominate dielectric properties of Cs2Au2X6.•Cs2Au2X6 with direct band gaps have wide visible light absorption.•Cs2Au2X6 possess potential applications as solar cells. In this work, we investigate the X-dependent crystal, electronic, elastic and optical properties of mixed-valence double perovskites Cs2Au2X6 (X=F, Cl, Br, I) based on first principles. The effects of all atomic sites, especially the [AuX2]− and [AuX4]− clusters with different valences of Au atoms, in the crystal structures of Cs2Au2X6 on their electronic and optical properties have been clarified. Meanwhile, Cs2Au2X6 double perovskites with direct band gaps have strong absorptions, low loss functions and low reflections, and they promise to be used as photoelectric absorption layers of solar cells.