Self-assembled interlayer aiming at the stability of NiOx based perovskite solar cells

Inorganic NiO x based inverted structure perovskite solar cells (PSCs) is reported to be more stable than that with the organic hole transport materials. In this work, NiO x /MAPbI 3 interface chemical reaction induced instability of perovskite is unveiled: Ni 3+ and I − exhibit redox reactions and deprotonation of MA + happens, which result in interface defects and perovskite lattice deformation. Thus the defective interface accelerates the degradation of perovskite by defect pathways from the bottom interface to the perovskite surface contacting H 2 O/O 2 . Self-assembled interlayer of NH 2 − end silane on NiO x separates the reactive NiO x and MAPbI 3 , tunes the interface energy states by –NH 2 end group. As a result, the PSC based on the silane treated NiO x achieves enhanced PCE of 20.1% with decent stability under environmental and extreme conditions (high temperature, high humidity, light infiltration). Our work highlights the interface chemical problem induced PSC instability and a simple interface modification to achieve the stable PSCs.