Computational Design of α-AsP/γ-AsP Vertical Two-Dimensional Homojunction for Photovoltaic Applications

Based on first-principles calculations, we design a α-AsP/γ-AsP homojunction with minimum lattice distortion. It is found that the α-AsP/γ-AsP homojunction has an indirect bandgap with an intrinsic type-II band alignment. The proposed α-AsP/γ-AsP homojunction exhibits high optical absorption of 1.6×106 cm-1 along the zigzag direction. A high power conversion efficiency (PCE) of 21.08% is achieved in the designed α-AsP/γ-AsP homojunction, which implies it has potential applications in solar cells. Under 4% in-plane axial strain along the zigzag direction, a transition from indirect band gap to direct band gap is found in the α-AsP/γ-AsP homojunction. Moreover, the intrinsic type-II band alignment can be tuned to type-I band alignment under in-plane strain, which is crucial for its potential application in optical devices.