First-principles prediction of stable Janus BiSbC3 monolayer with tunable electronic and optical properties under strain

In this study, first-principles calculations were used to study the structural, electronic and optical properties of a novel stable Janus BiSbC3 monolayer under varied biaxial strain levels. The structural and phonon dispersion calculations show that the novel Janus BiSbC3 is thermodynamically stable. At the equilibrium state, our results show that the Janus BiSbC3 monolayer is a direct semiconductor with a suitable energy band gap of 0.86 eV, which is converted to an indirect band gap with a biaxial tensile strain of +4%. It is worth noting that compressions strain of-8% causes a semiconductor-metal phase transition. The optical properties such as dielectric constant, reflectivity, extinction coefficient and absorption coefficient improved under biaxial strain with an enhanced absorption coefficient in the infrared and visible regions. Interestingly, a high absorption coefficient of 15.30 x 106 cm(-1) in the visible region under biaxial strain was predicted. Our calculations show that the novel Janus BiSbC3 monolayer has potential applications in optoelectronics and optical devices.