Effect of uniaxial strains on electronic and optical properties of SnSe from first-principles calculations

Abstract

In this work, we systematically investigate the uniaxial strain dependence of the electronic and optical properties of SnSe using first-principles calculations and the Bethe−Salpeter equation (BSE) approach. The calculated results show that uniaxial strains significantly affect the main peaks of density of states (DOS) in the valence band and conduction band through the influence on the densities of Sn s/p-states and Se p-state. The main peaks of the real ε1(ω) and imaginary ε2(ω) parts of the dielectric function can be enhanced by suitable uniaxial strains. In particular, the peaks of ε1(ω) and ε2(ω) along the a-axis increase by 34.8 % and 54.8 % with a red shift under the strain εa = −6 %, respectively. The high absorption coefficient in a wide energy range induced by uniaxial strains suggests a bright prospect for its applications in solar energy conversion. Our work indicates that strain engineering can be an efficient method to modulate the optical properties of SnSe and opens up a new avenue to its practical application.