The effects of Sc doping and O vacancy on the electronic states and optical properties of m-BiVO4

Author:

Huang Yuhong1,Zhang Xiaqing1,Wang Jingnan1,Zhang Jianmin1,Wei Xiumei1,Ma Fei2

Affiliation:

1. School of Physics & Information Technology, Shaanxi Normal University, Shaanxi Xi’an 710119, China.

2. State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Shaanxi Xi’an 710049, China.

Abstract

Based on density functional theory (DFT), the effects of scandium (Sc) doping and oxygen vacancy (VO) on the electronic states and optical properties of monoclinic BiVO4 (m-BiVO4) are investigated. The generalized gradient approximation plus U (GGA+U) method is adopted during the calculation of the electronic properties to compensate for the limitations of the DFT method. The ideal m-BiVO4 has a direct band gap of 2.400 eV, and if Bi in m-BiVO4 is substituted by Sc (subSc-Bi), the direct band gap will be reduced to 2.393 eV. However, if V is replaced by Sc (subSc-V) as well as oxygen vacancy induced (subSc–V+VO), the band gap will become indirect with values of 1.913 and 2.198 eV, respectively. The reduction capability is in the sequence of subSc–Bi > ideal > subSc–V+VO > subSc–V, while the oxidation capability is in the order of ideal > subSc–Bi > subSc–V+VO > subSc–V. The ε1(0) of the ideal, subSc–Bi, subSc–V, and subSc–V+VO defective m-BiVO4 are 8.290, 8.293, 12.791, and 8.285, respectively. The optical absorptions of ideal and subSc–Bi m-BiVO4 show anisotropy and they are nearly independent of the defect concentration. SubSc–V m-BiVO4 exhibits stronger absorption than the other three semiconductors. The absorptions of subSc–V+VO m-BiVO4 vary widely with the defect concentrations, where 3.906% defect concentration of m-BiVO4 has the strongest absorption. The estimated optical band gaps [Formula: see text] are smaller than Eg for ideal and defective m-BiVO4.

Publisher

Canadian Science Publishing

Subject

General Physics and Astronomy

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