Simplified p-i-n Perovskite Solar Cells with a Multifunctional Polyfullerene Electron Transporter

In prevailing p-i-n perovskite solar cells (PSCs), solution-processible fullerene molecules are widely used as electron-transporting layers (ETLs) but they typically suffer from poor uniformity and undesirable stability issues. Additionally, a separate bathocuproine (BCP) layer is needed to block hole transfer, increasing fabrication complexity and cost. Here, we address these limitations by developing a novel polymeric ETL (named PFBCP) synthesized by polymerizing C60 with BCP. This innovative material achieves both efficient electron transport and hole blocking, while its excellent uniformity minimizes interface recombination and enhances stability. Consequently, our blade-coated PSCs utilizing PFBCP achieve a high power conversion efficiency exceeding 22% and retain 91% of initial efficiency after 1200 h of light exposure. This development not only paves the way for commercially viable PSCs but also opens avenues for future ETL design to realize even more efficient and stable PSCs.