Overcome Low Intrinsic Conductivity of NiOx Through Triazinyl Modification for Highly Efficient and Stable Inverted Perovskite Solar Cells

Nickel oxide (NiOx) is a promising hole transport material in inverted organic‐inorganic metal halide perovskite solar cells. However, its low intrinsic conductivity hinders its further improvement in device performance. Here, we employ a trimercapto‐s‐triazine trisodium salt (TTTS) as a chelating agent of Ni2+ in the NiOx layer to improve its conductivity. Due to the electron‐deficient triazine ring, the TTTS complexes with Ni2+ in NiOx via a strong Ni2+‐N coordination bond and increases the ratio of Ni3+:Ni2+. The increased Ni3+ concentration adjusts the band structure of NiOx, thus enhancing hole density and mobility, eventually improving the intrinsic conductivity of NiOx. As a result, the device with TTTS modification displays a champion power conversion efficiency (PCE) of 22.81%. The encapsulated device based on a modified‐NiOx layer maintains 94% of its initial power output at the maximum power point and continuous one‐sun illumination for 1000 h at 45 °C. In addition, the unencapsulated target devices also maintain 92% at 60 ± 5% relative humidity and 25 °C in the air for 5000 h; and 91% at 85 °C in a nitrogen atmosphere for 1000 h. The research provides an effective strategy to enhance PCE and stability of inverted PSCs via modifying NiOx films with triazine molecule. We have introduced the trimercapto‐s‐triazine trisodium salt (TTTS) in the NiOx layer is introduced. The TTTS can coordinate with Ni2+ in NiOx via an electron‐deficient triazine ring to increase the concentration of Ni3+ and intrinsic conductivity of NiOx. The modified device achieves the best PCE of 22.81% and excellent operational, ambient and thermal stabilities.