First-principles study of the effect of alkali metals on the electronic and optical properties of SnS₂

Abstract

In this work, the electronic structure and optical properties of the monolayer SnS2 system have been doped with alkali metal atoms (X is Li, Na, K, and Rb) are investigated based on first-principles calculations of density functional theory. After the doping of alkali metal atoms, the bond lengths corresponding to the doped system increased compared to the pure SnS2 system. When alkali metal atoms are doped in the pure SnS2 system, the band gap value of the doped system increases and changes from an indirect band gap to a direct band gap. It is found that the density of states in the valence band near the Fermi energy level of all doped systems is primarily contributed by S atoms, and the conduction band is primarily contributed by Sn and S atoms. The polarizability of the doped SnS2systems is enhanced. Moreover, the absorption and reflection peaks of the SnS2doping system are redshifted, which improves the effective utilization rate of the infrared light region.