Governing PbI6 octahedral frameworks for high-stability perovskite solar modules

Abstract

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.