Governing PbI₆ octahedral frameworks for high-stability perovskite solar modules

Featuring soft ionic lattices of PbI6 octahedral frameworks, halide perovskites confront multiple occurrences of force-driven structural collapse (e.g., humidity, heat and illumination), initially on the surface and finally in the bulk, and ultimately protecting unstable PbI6 octahedral frameworks is necessary yet challenging in the process of perovskite–photovoltaic applications. Herein, a well-designed PbI6 octahedra-governing strategy with the functional synergism of cations and anions from vinylaniline trifluoromethanesulfonate has been implemented. On the one hand, the SO3CF3− anions simultaneously anchor uncoordinated Pb2+ cations and replace unstable I− ions on the PbI6 frameworks of the perovskite surface, effectively passivating the I− defects and stabilizing the PbI6 octahedral structure. On the other hand, poly(vinylaniline) cations obtained by the UV-induced polymerization of vinylaniline trifluoromethanesulfonate on the perovskite surface trigger compressive stress on the bulk-phase PbI6 frameworks and inhibit ion migration of I− under operating conditions. The anchoring-polymerization protection strategy is universal for modifying perovskite-involved multi-interfaces in large-area modules to tolerate harsh conditions (e.g., storage at 85 °C and 85% RH, working at 85 °C + one-sun illumination). Both high power conversion efficiency and stable continuous output on the as-modified modules were finally realized. Based on the above modules with multi-interfacial modification, a proof-of-concept outdoor automatic light-seeking photovoltaics-to-energy-storage system has been successfully demonstrated, showing great potential in building the future of stable and practical perovskite photovoltaics.