Cross-linkable fullerene interfacial contacts for enhancing humidity stability of inverted perovskite solar cells

In situ cross-linking encapsulation has been demonstrated to be an efficient strategy for enhancing the humidity stability of perovskite solar cells(PSCs).In this study,a novel cross-linkable fullerene derivative,namely1-(p-benzoate-(p-methylvinylbenzene)-indolino[2,3][60]fullerene(FPPS),was readily synthesized from commercially available building blocks in two steps.This FPPS was employed as an interfacial modifier on perovskite surfaces in inverted planar p-i-n PSCs.Owing to the fast interfacial charge extraction and efficient trap passivation,PSCs based on the cross-linked FPPS(C-FPPS)exhibited excellent performance.The PSCs had a top-performing power conversion efficiency(PCE)of 17.82%with negligible hysteresis,compared to the control devices without C-PFFS(16.99%).Moreover,the strong water resistance of the C-FPPS interfacial layer distinctly enhances the ambient stability of PSC devices,exhibiting a t80(the time required to reach 80%of the initial PCE)of 300 h under high-humidity conditions.This significantly surpasses the control devices,whose t80 was only 130 h.These results demonstrate that cross-linkable fullerene derivatives can be promising interfacial materials for designing high-efficiency,hysteresis-free,air-stable PSCs.