Investigation on buried interfacial charge carrier dynamics of the MAPbI3/NiO interface by mismatch strain and termination

Organic-inorganic halide perovskite solar cells (PSCs) have attracted significant attention due to their low cost, simple fabrication process, and rapid improvement in photovoltaic performance. NiO is often considered as a potential hole transport layer (HTL) in these PSCs owing to its wide band gap and deep valence band level. However, uncertainties remain regarding the interfacial charge carrier dynamics at the perovskite/HTL interface induced by the interfacial mismatch strain and terminal configuration. Herein, typical MAPbI3/NiO interfacial terminal configurations (MAI-Ni, MAI-O, PbI-Ni, PbI-O) with strain-configured interfaces were explored by first-principle and device simulation. The results indicate that the binding energy decreases, the carrier transport efficiency increases, and the valence band offset (VBO) decreases as the interfacial atomic configuration of the perovskite surface changes from MAI to PbI. Meanwhile, the compressive strain applied on the perovskite surface also increases the interfacial VBO. The J-V curves and energy band of the PSCs show that the device performance tends to enhance first and then decrease as the positive VBO of the MAPbI3/NiO interface increases. Thus, the strain and termination configuration could modulate the device's photovoltaic performance, which is dependent on the energy band bending caused by the strain and termination configuration. This work provides a valuable understanding of the MAPbI3/NiO interface and contributes new strategies to interface optimization for further improving the photoelectric conversion efficiency of PSCs.