First-principles calculations to investigate structural, electronic and optical properties of Janus AsMC3 (M: Sb, Bi) monolayers for optoelectronic applications

Abstract

Janus monolayers as novel 2D materials have attracted considerable attention owing to their excellent properties. In this present study, first-principles calculations are used to study the electronic structure and optical properties of As2C3 and Janus AsMC3 (M: Sb, Bi) monolayers. The electronic calculations showed that the As2C3 and AsBiC3 and AsSbC3 Janus monolayers exhibited a bandgap of 1.44, 0.99, and 1.16 eV, respectively. The conduction band minimum (CBM) and the valence band maximum (VBM) are shifted toward the Fermi level without changing the bandgap for As2C3 and AsSbC3 when including spin-orbit coupling (SOC). The phonon dispersion calculations confirmed that these structures are dynamically stable. Moreover, the optical properties such as the real part ε1(ω) and imaginary part ε2(ω) of the dielectric constant, refractive index n(ω), reflectivity R(ω), extinction coefficient K(ω) and absorption coefficient α(ω), versus the energy are determined. Interestingly, it is found that the Janus structures of AsBiC3 and AsSbC3 revealed excellent optical absorption, indicating that the predicted Janus structures with a suitable direct bandgap are promising candidates for photovoltaic and optoelectronic applications.