First‐Principles Study of the Electronic and Optical Properties of Bi2Se3/MoSe2 Heterojunction

MoSe 2 and Bi 2 Se 3 are two kinds of 2D materials that are gradually receiving more attention because of their unique electronic and optical properties. Herein, a Bi 2 Se 3 /MoSe 2 van der Waals heterojunction (vdWH) is constructed and the electronic and optical properties of the heterojunction are calculated using first‐principles calculations. The effects of the external electric field and the interlayer distance on the electronic properties of the heterojunction are also studied. The calculated results show that the inherent Bi 2 Se 3 /MoSe 2 vdWH has a type‐2 band alignment with a very small indirect bandgap (28 meV). It also has strong spin–orbit coupling effects, and the characteristics of Zeeman splitting and Rashba splitting are observed at the same time. Both applying an external electric field and changing the interlayer distance can effectively modulate the band structure of the heterojunction; these modulation methods can change the band alignment of the vdWH from type‐2 to type‐3 or even type‐1, and the bandgap type can be changed from indirect to direct. The infrared absorption of the heterojunction is much higher than that of Bi 2 Se 3 and MoSe 2 . All the calculation results show that the Bi 2 Se 3 /MoSe 2 vdWH has good application prospects in optoelectronic and spintronic devices.