First principles study of electronic and optical properties of inorganic and lead-free perovskite: Cs3Bi2X9 (X: Cl, Br, I)

• Published in: Materials chemistry and physics 2020-10, Vol.253, p.123374, Article 123374
• Main Authors: Luo, Taiming, Wei, Jianwei
• Format: Article
• Language: English
• Subjects: Absorptivity; Crystal structure; Cs3Bi2X9; Density functional theory; Electron states; Electronic devices; First principles; Lead free; Optical properties; Perovskite; Perovskites; Photoluminescence; Surface structure; The first principles
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2020.123374

The inorganic lead-free perovskite has a great potential for opt-electronic devices and cheap synthesis. The electronic and optical properties of the Cs3Bi2X9 (X: Cl, Br, I) were explored by density functional theory in order to understand the essence of the optical properties. The electrical structure and absorption coefficient were calculated for the crystals with or without vacuum layer. Our results reveal that the optical properties are dominated by the electronic states of Bi and X around Fermi level. The optical absorption is sensitive to the surface structure of Cs3Bi2Cl9, but not to that of Cs3Bi2Br9 and Cs3Bi2I9. The Cs3Bi2Br9 has the better potential than other two materials to be modified on the photoluminescence in visible range. •Optical properties are significantly modulated by surface structures.•Three materials were systematically studied for the first time.•Cs3Bi2Cl9, Cs3Bi2Br9 have large potential for improvement in optical and band.