2D XBiSe3(X = As, Sb) monolayers with high anisotropic mobility and enhanced optical absorption in visible light region

Abstract

Configurations and properties of 2D XBiSe3(X = As, Sb) monolayers are predicted by first-principles calculations. Dynamic and thermal stabilities are affirmed by phonon dispersion and ab initio molecular dynamics simulation, respectively. Bandgap and band edges, density of states, optical absorptions, and mobilities are calculated by using the obtained structures. Effects of strain engineering on the band structure and optical absorption are also explored. Results reveal that the AsBiSe3 and SbBiSe3 monolayers have indirect gaps of 1.2 eV (HSE06)/1.43 eV (GW) and 1.1 eV (HSE06)/1.32 eV (GW), respectively. The high electron (approximately 105 cm2V−1s−1) and hole (approximately 104 cm2V−1s−1) mobilities of the XBiSe3 monolayers are observed for zigzag and armchair directions, and obvious anisotropy is observed. The intense optical absorptions in the UV–visible light regions are identified for the two monolayers. Interestingly, the band edge of the AsBiSe3 monolayer can span the redox potential of water under −4% biaxial compressive strain, which implies that this monolayer can be used as a candidate material for photocatalytic water splitting to produce hydrogen. All the results support the assertion that the XBiSe3 monolayers have potential for application in the optoelectronic, photocatalytic, and photovoltaic fields.