Synergetic Strategy for Highly Efficient and Super Flexible Thick‐film Organic Solar Cells

Abstract Efficient organic solar cells (OSCs) equipped with thick‐film active layers and high flexibility are of great significance for industrial preparation and practical applications. Herein, a ternary strategy coupled with a functional additive is employed to obtain efficient thick‐film flexible OSCs. A novel polymer donor PBB1‐F with good planarity is synthesized as a third component to optimize photon capture and molecular stacking. Meanwhile, a high dielectric constant polyarene ether (PAE) functional additive with strong adhesion not only greatly improves exciton dissociation efficiency, but also acts as locking cage‐like for effective enhancement of the mechanical stability of active layer. As a result, the PM6:PBB1‐F:Y6‐BO‐4Cl and PM6:PBB1‐F:BTP‐eC9 based ternary OSCs with PAE exhibit an efficiency of 17.91% and 18.51% under rigid thin‐film state, and perform better under thick‐film state of rigid (16.40% and 16.84%) and flexible (14.78% and 14.95%). Under the protection of the polymers, tight entanglement and cage‐like PAE adhesion, the elongation at break of the active layer increases by more than fourfold (27.3%), and gives a super flexible thick‐film OSCs that maintains more than 90% performance after 1000 bending cycles with a diameter of 10 mm. Overall, this work provides a new feasible scheme to effectively solve thickness sensitivity and flexibility issues in the context organic photovoltaic applications.