Strain tunable electronic and optical properties of 2D orthorhombic lithium sulfur monolayer

The stability, electronic and optical properties of possible two-dimensional (2D) Li2S monolayer with orthorhombic atomic configuration denoted as O-Li2S monolayer is theoretically investigated. It is shown that the proposed 2D O-Li2S monolayer exhibits the space group of 59_Pmmn and is energetically and kinetically stable. Our electronic properties computations indicate that 2D Li2S monolayer is a wide band gap (WBG) semiconductor with a strain tunable direct band gap of 4.13 eV obtained from HSE06 level of theory. Calculating its optical properties show that this newly designed 2D O-Li2S monolayer has high absorption property in ultra violet region of light.