Misplaced-dipole engineered repairable fluoropolymer elastomer for flexible perovskite solar cell with excellent thermal-mechanical cycling resistance

Flexible perovskite solar cells (F-PSCs) offer a compelling solution to the intrinsic rigidity of silicon-based photovoltaics, enabling power generation on irregular surfaces. However, their practical application hinges on the perovskite layer’s ability to concurrent thermal cycling, so as to match the deformability of polymer substrates. Different from the conventional lattice solidification strategy for rigid devices, we incorporate a fluorinated misplaced-dipole engineered repairable elastomer into the perovskite film, which enhances perovskite intergranular toughness and mitigates thermal stress fatigue cracks. The resultant perovskite film exhibits suppressed lattice thermal fluctuation, thereby boosting enhanced environmental resilience. Consequently, the optimized F-PSCs deliver a champion efficiency of 25.54%, versus 26.83% for their rigid counterparts. More importantly, the F-PSC demonstrates exceptional durability under harsh operational stresses, retaining over 90% of the initial PCE after 11,000 bending cycles and maintaining a comparable retention rate following 500 thermal cycles, paving the way towards for the long-lasting flexible photovoltaic devices. Flexible perovskite solar cells work on curved surfaces but bending and heat cycling induce stress and cracks in the perovskite layer. Liu et al. add a fluorinated repairable elastomer to toughen grain boundaries, limit thermal strain, and deliver high efficiency with durable operation.