First-principles study on the electronic structure and optical properties of BiOBr

By adopting the first principle method based on density functional theory framework, the geometric structure, electronic structure and optical properties of BiOBr were studied by generalized gradient approximate. Theoretical calculation results have shown that BiOBr is an indirect wide-band gap semiconductor material with a band gap width of 2.19 ev. The analyses of state density and atomic charge arrangement number have shown that the valence band top of BiOBr is mainly contributed by 4p orbitals of O 2p and Br 4p, while the lowest conduction band is mainly formed by Bi 6p orbital. In addition, the charge density has revealed that BiOBr is a hybrid bond semiconductor with strong covalent and weak ionic properties, and has a strong p orbital distribution. The calculation results of optical properties have shown that two obvious dielectric peaks appear in the energy range of 0-15 eV, and the absorption band edge is 448 nm, which is consistent with the experimental results. The above outcomes have the theoretical guiding significance for exploring the potential applications of BiOBr materials, and provide theoretical basis for us to accurately monitor and control the growth of BiOBr materials.