Pb and Li co-doped NiOx for efficient inverted planar perovskite solar cells

Organic-inorganic halide perovskites solar cells have garnered increasing attention in recent years due to the dramatic rise in power conversion efficiencies (PCEs). In perovskite solar cells (PSCs), selecting appropriate hole transport materials to insert between perovskite layer and electrodes can improve Schottky contact, facilitate the hole transport, therefore reduce charge recombination, and therefore improve cell performance. Doping of metal cation is an effective means to regulate energy level structure and change its conductivity. In this study, we novelly introduce the Pb²⁺ doped NiOx as the hole transport materials to decrease the energy loss between NiOx and the perovskite layer, which improves open-circuit voltage (Voc) of the PSCs. In order to improve the conductivity of the NiOx film, the Li⁺ co-doping is introduced. We introduce Pb and Li co-doping strategy to match the work function of doped NiOx with perovskite valence band energy level, and increase the conductivity of NiOx for high-efficiency inverted planar PSCs. The Pb and Li co-doped NiOx devices exhibit efficient hole extraction and enhanced conductivity, which improve the performance of inverted planar PSCs to 17.02% compared with 15.40% of the undoped device.