Interfacing Pristine C₆₀ onto TiO₂ for Viable Flexibility in Perovskite Solar Cells by a Low‐Temperature All‐Solution Process

A low‐temperature solution‐processed strategy is critical for cost‐effective manufacture of flexible perovskite solar cells (PSCs). Based on an aqueous‐processed TiO 2 layer, and conventional fullerene derivatives replaced by a pristine fullerene interlayer of C 60 , herein a facile interface engineering for making all‐solution‐processed TiO 2 /C 60 layers in flexible n‐i‐p PSCs is reported. Due to the improvement of the perovskite grain quality, promotion of interfacial charge transfer and suppression of interfacial charge recombination, the stabilized power conversion efficiency for the flexible PSCs reaches as high as 16% with high bending resistance retention (≈80% after 1500 cycles) and high light‐soaking retention (≈100% after 100 min). In addition, the stabilized efficiency is over 19% for the rigid TiO 2 /C 60 ‐based PSCs. The present work with the facile low‐temperature solution process renders the practicability for high‐performance flexible PSCs applied to wearable devices, portable equipment, and electric vehicles.