Modulation of monolayer SnSe2 optoelectronic properties by applied electric field and atomic doping

Based on the first principles, we have calculated the influence of the applied electric field and doped X (X = N, P, As, Sb) atoms on the optoelectronic properties and phonon dispersion of the monolayer 2D material SnSe₂. The calculation results show that intrinsic SnSe₂ is a semiconductor with a band gap value of 0.884 eV. The doping of X atoms improves the energy band tunability of the monolayer SnSe₂ system and becomes more stable. The N-doped SnSe₂ system has the most stable structure and the best doping performance. When the electric field strength of 0.3 V/Å is applied on the surface of the N-doped system, the band gap of the system increases. The energy gap gradually decreases when the electric field strength continues to increase from 0.3 V/Å to 0.9 V/Å. At an applied electric field strength of 0.9 V/Å, the system changes from semiconductor to metallic properties. As far as the optical properties are concerned, the applied electric field increases the static refractive index of the system, the imaginary part of the photoconductivity increases, the energy loss function decreases, and the light absorption performance improves. The applied electric field successfully enhanced the optical properties of the SnSe₂ system. The applied electric field strength of 0.9 V/Å doped N system has the best optical properties. This provides a new way to explore the optoelectronic devices based on the SnSe₂ doped system.