Ambient scalable fabrication of high-performance flexible perovskite solar cells

Flexible perovskite solar cells (F-PSCs) are increasingly being recognized for their high specific power density and mechanical flexibility. However, the feasibility of large-scale production via low-cost ambient printing towards high-performance cells and large modules remains under-explored. Herein, we succeed in ambient printing of perovskite films for high-performance F-PSCs by utilizing a novel ionic liquid, 1-butyl-3-methylpyridine thiocyanate (BPySCN), to address challenges associated with ambient moisture interference and poor crystallization quality at low-temperature processing. This functional additive, containing dual ionic components with electron-donating properties, plays multiple functional roles at different stages of device fabrication. The strong coordination affinity between BPySCN and perovskite modulates crystallization to reduce the nucleation density during low-temperature ambient printing, and retard the crystal growth in the annealing step to regulate the composition homogeneity and mitigate stain residue within films. After annealing, the residual ionic liquid uniformly distributed throughout perovskite films helps to passivate defects, leading to more efficient charge transport and suppressed energy loss. As a result, the small-area (0.09 cm 2 ) PSCs on both rigid and flexible substrates achieve power conversion efficiencies (PCEs) of 23.70% and 23.01%, respectively, and the 117.0 cm 2 -scale flexible module delivers a high PCE of 17.52% (certified 15.30%) with an impressive specific power density of 1969.1 W kg −1 (certified 1705.3 W kg −1 ), which are all among the highest in their respective categories. Furthermore, the potential for wearable electronics was demonstrated through integrated devices, representing a significant advancement in the commercial progress of F-PSCs. Ionic-liquid mediated scalable ambient-printing for efficient perovskite solar modules to achieve wearable electronic integration.