Effects of doping Ti, Nb, Ni on the photoelectric properties of monolayer 2H–WSe2

The photocurrent of Ti, Nb, Ni substitution-doped monolayer 2H–WSe2 is calculated by the first-principles method based on the Keldysh nonequilibrium Green's function-density functional theory. The photogalvanic effect(PGE) photocurrent can be generated in the monolayer 2H–WSe2 under the vertical irradiation of linear polarized light, However, it is generally very small. Calculation results show that the Nb and Ti-doped systems exhibit the characteristics of semi-metal, while the Ni-doped system tends to transform into metals. The substitutional doping of Nb, Ti, and Ni atoms can effectively enhance the photocurrent and the polarization sensitivity of monolayer 2H–WSe2.This excellent performance is mainly attributed to the fact that the doping introduces multiple impurity energy bands crossing the Fermi energy level, which becomes a bridge for electronic transitions, thus effectively enhancing the photocurrent.