One-step-fabricated flexible perovskite quantum dot solar cells via sequential ligand exchange

Flexible perovskite solar cells (f-PSCs) are desired for portable electronic applications owing to their light weight and high power-to-weight properties. Nevertheless, the development of perovskite quantum dots (PQDs)-based flexible solar cells is still lagging behind. Herein, a sequential ligand exchange strategy induced by dipropylamine (DPA) and benzoic acid (BA) is proposed to treat the surface chemistry of FAPbI 3 PQDs, which enables to realize efficient and stable flexible PQD solar cells through one-step-fabricated techniques. The FAPbI 3 PQD films exhibit enhanced electronic coupling and suppressed carrier non-radiation recombination, contributing to the efficient flexible FAPbI 3 PQD solar cells with an impressive power conversion efficiency (PCE) of 12.13 % (14.27 % on the rigid substrate) on a 0.06 cm 2 scale, 11.13 % on a 0.12 cm 2 scale, 10.33 % on a 0.49 cm 2 scale, and 9.96 % on a 0.98 cm 2 scale, along with improved environmental stability. Meanwhile, the corresponding flexible PQD device maintained ∼90 % of its initial PCE after 100 bending cycles (7 mm bending radius). Moreover, systematic studies further reveal that ligand-capped PQDs exhibit extraordinary mechanical stability compared to bulk thin films, compatible well with flexible photovoltaic applications. This work contributes to a new avenue for developing high-performance QD flexible electronics in the foreseeable future.