Design and analysis of III-V two-dimensional van der Waals heterostructures for ultra-thin solar cells

Van der Waals (vdW) heterostructures consist of six group III-V monolayers MX (M = Ga, In, X = P, As, Sb) have been systematically investigated via hybrid functional HSE06 based on DFT calculations in order to evaluate their utilities in potential solar cell materials. 24 different stacking configurations for the 15 heterostructures each, with a total of 360 different structure models, are designed and discussed. These vdW heterostructures are found to be energetically favorable with formation energies, calculated using DFT-D3 method, vary from −1.5 eV to 0.5 eV. The energetic and electronic properties of these heterostructures are examined. Our results show that the stacking model BB-3 for most heterostructures holds suitable type-II bandgaps around 1.1 eV, which guarantee the potential for solar cell applications. Furthermore, the power conversion efficiencies (PCEs) for GaSb/InSb and GaAs/InAs are found to reach 22.88% and 20.65% respectively. The optimal bandgap size, efficient optical absorption with ultrahigh photoresponsivity enable these materials to be promising candidates in optoelectronic devices.