Suppressing Redox Reactions at the Perovskite-Nickel Oxide Interface with Zinc Nitride to Improve the Performance of Perovskite Solar Cells.

For p-i-n perovskite solar cells (PSCs), nickel oxide (NiO) hole transport layers (HTLs) are the preferred interfacial layer due to their low cost, high mobility, high transmittance, and stability. However, the redox reaction between the Ni and hydroxyl groups in the NiO and perovskite layer leads to oxidized CHNH and reacts with PbI in the perovskite, resulting in a large number of non-radiative recombination sites. Among various transition metals, an ultra-thin zinc nitride (ZnN) layer on the NiO surface is chosen to prevent these redox reactions and interfacial issues using a simple solution process at low temperatures. The redox reaction and non-radiative recombination at the interface of the perovskite and NiO reduce chemically by using interface modifier ZnN to reduce hydroxyl group and defects on the surface of NiO. A thin layer of ZnN at the NiO/perovskite interface results in a high Ni/Ni ratio and a significant work function (WF), which inhibits the redox reaction and provides a highly aligned energy level with perovskite crystal and rigorous trap-passivation ability. Consequently, ZnN-modified NiO-based PSCs achieve a champion PCE of 21.61%, over the NiO-based PSCs. After ZnN modification, the PSC can improve stability under several conditions.