Pre-Anchored Ionic Bond Mediators Enabling Controllable Monolayer Assembly for High-Performance Perovskite Solar Cells and Modules.

Abstract

Self-assembled monolayer (SAM) has emerged as an indispensable hole-selective contact for high-efficiency perovskite solar cells (PSCs). However, the formation of dense, uniform SAMs via wet deposition poses challenges due to two thermodynamically feasible yet competing processes: the self-aggregation of SAM molecules and chemisorption-driven substrate anchoring. Herein, a rapid and controllable strategy for SAM assembly is presented, enabled by pre-adsorbed ionic bond mediators. The pre-anchored arginine (Arg) molecules on nickel oxid (NiO_x) can weaken the amphiphilic nature of SAM molecules through ionic bond interaction, while also acting as steric barriers, thereby suppressing the self-aggregation of SAM molecules. This strategy is compatible with both spin-coating and blade-coating techniques, enabling rapid and controllable assembly of high-quality SAM of [4-(3,6-dimethyl-9H-carbazol-9-yl) butyl] phosphonic acid. Moreover, the polar guanidinium tail of Arg passivates defects at the buried perovskite interface while strengthening interfacial coupling with the perovskite layer-enhancing both mechanical stability and electrical contact. Benefiting from these synergistic effects, the PSCs achieve high PCEs of up to 26.67% and 21.05% for small-area devices (active area: 0.049 cm²) and large-area modules (active area: 64.68 cm²), respectively. Notably, the devices exhibit exceptional operational stability, retaining 93% of their initial PCE after 1700 h of maximum power point tracking under the ISOS-L-2 protocol.