Al doping effect on optoelectronic and thermoelectric properties of h-ZnS monolayer: a DFT approach

Al-doped hexagonal ZnS monolayer (h-ZnS-2D) at different concentrations is adopted by using Density Functional Theory (DFT) to show the effect of Al doping on the optoelectronic and thermoelectric performances of h-ZnS-2D. The optimized cells give planar structures with small decrease of the lattice parameter and a n-type conductivity with a direct band gap, which increasing with Al content. An improvement of absorption and reflectivity and a decrease in transmittance are observed with doping in the visible and IR ranges. The thermoelectric properties showed a negative Seebeck coefficient justifying the n-type conduction and an enhancement of electrical conductivity and power factor for an optimum Al concentration of 12.5%. At high Al content, the formation of additional insulating phase of Al2S3 explains the degradation of the properties. This study opens the way to use these doped monolayers as a potential candidate in the optoelectronic applications and for thermoelectric power generation.