Photoelectric properties of monolayer NbS2 and NbSe2 under three types of strain: A first-principles study

Abstract

Based on the first principles, the crystal structure, photoelectric properties, and structural stability of two transition metal dichalcogenides (TMDCs) under different strain treatments are systematically calculated. The properties of NbX2 under tensile and compressive strains are discussed for the first time. Recently, a single-layer 1T structure with X atoms surrounding the transition metal atoms was synthesized in experiments. The 1T multi-forms were octahedral coordination structures, and some of the systems showed excellent semiconductor properties and stability. The results show that NbS2 has an indirect band gap under different strains and tends to transition to semiconductors which can effectively improve the material activity. NbSe2 has more excellent properties in the optical field and can be used to manufacture infrared lenses, anti-reflection coatings, and UV reflectors. This study provides a new understanding of the unconventional structure of NbX2 and provides theoretical guidance for the work in the field of TMDCs.