Electronic structure and optical properties of bismuth chalcogenides Bi2Q3 (Q = O, S, Se, Te) by first-principles calculations

Bismuth chalcogenides, including: Bi 2 O 3 , Bi 2 S 3 , Bi 2 Se 3 , and Bi 2 Te 3 , are important photoelectric functional materials, and have a wide range of applications. In this article, first-principles calculations were performed to investigate the crystal structure, electronic properties, and optical properties of these compounds. The relationship between crystal micro-structure, electronic structure, and optical properties has been systematically investigated. On one hand, from Bi 2 O 3 to Bi 2 Te 3 , with the increasing atomic number of the Group VI elements, the electronic structures and optical properties exhibit obvious similarities and tendencies. The bonding varies within the series from strongly ionic in the oxide of Bi 2 O 3 , to iono-covalent in the sulfide of Bi 2 S 3 and selenide of Bi 2 Se 3 , to weak covalent and Van der Waals in the teliuride of Bi 2 Te 3 . Owing to the difference between chain-like structure and layered structure, the gain of electrons of Se atoms in Bi 2 Se 3 with orthorhombic structure is more than that of in Bi 2 Se 3 with trigonal structure. Based on the calculated results, it is found that the optical properties are determined by the components of the bismuth chalcogenide compounds as well as the micro-structure of the bismuth chalcogenide compounds. These calculated results can provide reliable data and support for the development of new bismuth-based optoelectronic materials and devices.