Gold Nanoparticles Functionalized with Fullerene Derivative as an Effective Interface Layer for Improving the Efficiency and Stability of Planar Perovskite Solar Cells

Titanium dioxide (TiO 2 ) is an extensively used electron transporting layer (ETL) in n–i–p perovskite solar cells (PSCs). Although, TiO 2 ETL experiences the high surface defect together with low electron extraction ability, which causes severe energy loss and poor stability in the PSC. In this study, a new intermediate layer consisting of gold nanoparticles functionalized with fully conjugated fullerene C 60 derivative (C 60 ‐BCT@Au NPs) that enhances the interfacial contact at ETL/perovskite interface leading to a perovskite film with improved crystallinity and morphology is reported. Moreover, the studies demonstrate that the interface modification of the TiO 2 ETL with C 60 ‐BCT@Au NPs substantially improves the charge extraction efficiency from the perovskite layer and suppresses charge recombination processes. Consequently, the resulting device yields a champion efficiency of 19.08% as well as devaluation in hysteresis. In addition, the unencapsulated PSCs with c‐TiO 2 /C 60 ‐BCT@Au NPs ETL retain 83% and 90% of their original PCEs after 500 h storage in air and exposure to continuous UV illumination for 200 h, respectively. This study provides an effective method to address the electron transporting issues between perovskite and c‐TiO 2 ETL for developing stable and efficient PSCs.