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

Abstract

AbstractFor p‐i‐n perovskite solar cells (PSCs), nickel oxide (NiOx) 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≥3+ and hydroxyl groups in the NiOx and perovskite layer leads to oxidized CH3NH3+ 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 (Zn3N2) layer on the NiOx 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 NiOx reduce chemically by using interface modifier Zn3N2 to reduce hydroxyl group and defects on the surface of NiOx. A thin layer of Zn3N2 at the NiOx/perovskite interface results in a high Ni3+/Ni2+ 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, Zn3N2‐modified NiOx‐based PSCs achieve a champion PCE of 21.61%, over the NiOx‐based PSCs. After Zn3N2 modification, the PSC can improve stability under several conditions.