Hydroxyl Interfacial Engineering for Self-Assemble Monolayers Anchoring on NiOx Enables Efficient and Stable Perovskite Solar Cells.

The performance of inverted perovskite solar cells (PSCs) is critically constrained by interfacial losses arising from the insufficient coverage and weak adhesion of self-assembled monolayers (SAM). Herein, we report a SAM regulation strategy by mixing hydroxylated V2CTx MXene (V2C-OH) with nickel oxide (NiOx), which can provide abundant hydroxyl sites for SAM anchoring, thereby forming a uniform and dense SAM layer. First-principles calculations further reveal that the binding energy between SAM and hydroxyl groups on V2C-OH is stronger than that on pristine NiOx, explaining the enhanced thermal stability of SAM on the hybrid substrate. Meanwhile, the highly ordered and tightly packed SAM layer promotes vertical growth and [001]-preferred orientation of perovskite grains. Therefore, the introduction of V2C-OH enables a top-down modulation of the NiOx, SAM, and perovskite layers, improving their morphology and interfacial properties. The resulting PSCs achieve a champion power conversion efficiency of 26.6% (certified at 26.2%) for a 0.0524 cm2 device and 24.7% for a 1 cm2 device, along with outstanding long-term operational stability.