Structural, electronic, and optical properties of type II heterostructure based on WS2/black phosphorene

Structural, electronic and optical properties of WS₂/Black Phosphorene heterostructure have been explored using the abinitio simulation based on density functional theory (DFT). An interlayer separation of 3.1 Å at equilibrium is found for the optimized heterostructure with the lowest binding energy. This suggests strong van-der Waal (vdW) interconnections in the relaxed heterostructure. The electronic properties of the optimized heterostructure are studied by calculating the band structure and density of states (DOS) plots. Band structure calculation for the monolayer WS₂/Black Phosphorene heterostructure shows an indirect energy gap behaviour having value around 0.79 eV. To explore the optical characteristics of the relaxed heterostructure, Kubo-Greenwood formalism in a combination with DFT is used. The absorption coefficient, Dielectric constant and refractive index are calculated for the heterostructure. The absorption coefficient spectrum lies in the ultraviolet region for individual WS₂ monolayer and black phosphorene. While the relaxed heterostructure based on monolayer WS2/Black Phosphorene shows its absorption coefficient spectrum in both visible (~380-420 nm) and ultraviolet region. Redshift phenomena have been observed for the relaxed heterostructure. Other optical properties like refractive index and dielectric constant are also in accordance with the absorption coefficient. Further, Type II energy band alignment has been found for the relaxed heterostructure. These calculated results suggest its potential applications in the designing of novel optoelectronic devices.