Computational discovery of PtS2/GaSe van der Waals heterostructure for solar energy applications.

2D van der Waals (vdW) heterostructures as potential materials for solar energy-related applications have been brought to the forefront for researchers. Here, by employing first-principles calculations, we proposed that the PtS2/GaSe vdW heterostructure is a distinguished candidate for photocatalytic water splitting and solar cells. It is shown that the PtS2/GaSe heterostructure exhibits high thermal stability with an indirect band gap of 1.81 eV. We further highlighted the strain induced type-V to type-II band alignment transitions and band gap variations in PtS2/GaSe heterostructures. More importantly, the outstanding absorption coefficients in the visible light region and high carrier mobility further guarantee the photo energy conversion efficiency of PtS2/GaSe heterostructures. Interestingly, the natural type-V band alignments of PtS2/GaSe heterostructures are appropriate for the redox potential of water. On the other hand, the power conversion efficiency of ZnO/(PtS2/GaSe heterostructure)/CIGS (copper indium gallium diselenide) solar cells can achieve ∼17.4%, which can be further optimized up to ∼18.5% by increasing the CIGS thickness. Our present study paves the way for facilitating the potential application of vdW heterostructures as a promising photocatalyst for water splitting as well as the buffer layer for solar cells.