Covalent Tridentate Molecule Anchoring Enhances Nickel Oxide for Efficient Perovskite Solar Cells

Nickel oxide (NiO_x) is a promising hole transport material for perovskite solar cells, but its high surface defect density and energy level mismatch with perovskite limit device efficiency. Conventional organic surface modifiers, relying on weak hydrogen bonds or single covalent bonds, fail to anchor stably to NiO_x, hindering their functional effectiveness. Here, A multidentate anchoring organic molecule, [4-(trifluoromethyl)phenyl]triethoxysilane (3F-PTES), is presented, forming robust tridentate covalent bonds with the NiO_x surface and significantly enhances interfacial binding strength and surface coverage compared with conventional groups (e.g., carboxyl). As a result, the interfacial defect density is reduced by 2.5-fold compared with carboxyl-modified counterparts and significantly suppresses the deprotonation reaction between NiO_x and perovskite, thereby greatly improving interfacial contact. The designed trifluoromethyl terminal group further enables precise tuning of NiO_x energy levels, achieving near-ideal band alignment with perovskite (energy offset ΔE = 0.01 eV). Incorporating this modified NiO_x into inverted devices, a champion power conversion efficiency (PCE) of 26.47% is achieved, along with outstanding operational stability, retaining 97% of their initial efficiency after 1500 h of continuous operation under maximum power point tracking (65 °C, 60% relative humidity, AM 1.5G illumination, ISOS-L-3 protocol).