Tailored multi-functional molecular chain-based ferrocene derivative for efficient and stable perovskite solar cells

Under the stimulation of external factors, the ions with small activation energies could escape from the surface of perovskite , aggravating the defects at the interfaces and deteriorating the perovskite solar cells (PSCs). Here, we report a novel strategy utilizing a tailored organometallic molecule (bis-ferrocenyl-carboxylate-hexadecafluorodecyl, namely Fc-16 F) interlayer to functionalize the perovskite/hole transport layer interface , which simultaneously blocks the migration pathways of ions and facilitate the charge extraction at the interface. The electron-absorbing substituents (carboxyl groups and a long C-F chain) are introduced to strengthen the redox properties of ferrocene units, limit self-migration, and enhance hydrophobicity . With the strengthened oxidation driving force and the tight and dense hydrogen bond networks formed between Fc-16 F and organic cations, Fc-16 F could efficiently recover the Pb, I vacancies, inhibit the diffusion of defect-induced by-products (I 2 ), and stabilize the components on the surface. The champion device modified with Fc-16 F interlayer yields a remarkable power conversion efficiency (PCE) of 23.02% as well as superior humidity and long-term stabilities. The Fc-16 F-modified PSCs retain an outstanding 83.3% of its initial PCE over 1200 h under high humidity (60% RH) and retain over 90% of its initial PCE after aging in the N 2 atmosphere for over 2000 h.