Synergistic Toughening and Self-Healing Strategy for Highly Efficient and Stable Flexible Perovskite Solar Cells

摘要

Halide perovskites are qualified to meet the flexibility demands of optoelectronicfield because of their merits of flexibility, lightness, and low cost.However, the intrinsic defects and deformation-induced ductile fracture inboth perovskite and buried interface significantly restrict the photoelectricperformance and longevity of flexible perovskite solar cells (PVSCs). Here,a dual-dynamic cross-linking network is schemed to boost the photovoltaicefficiency and mechanical stability of flexible PVSCs by incorporating naturalpolymerizable small molecule α-lipoic acid (LA). The LA therein can be autonomouslyring-opening polymerized through dynamic disulfide bonds andhydrogen bonds, concurrently forming coordination bonds to interact withperovskite component. Importantly, the polymerization product can serveas efficacious passivating and toughening agents to simultaneously optimizeinterfacial contact, enhance perovskite crystallinity and sustain robustmechanical bendability. Subsequently, the rigid (or flexible) p-i-n device realizesa champion efficiency of 22.43 (or 19.03) with prominent operationalstability. Moreover, the dual-dynamic cross-linking network endows PVSCswith bendability and self-healing capacity, allowing the optimized devices toretain >80 efficiency after 3000 bending cycles, and subsequently restore to≈95 of its initial efficiency under mild heat-treatment. This toughening andself-healing strategy provides a facile and efficient path to prolong operationallifetime of flexible device.