Electron-Transporting\nPolymer with Perfluoroalkyl\nSpacer Enables Efficient and Stable Non-Fullerene Organic Solar Cells

To achieve efficient and stable organic solar cells (OSCs),\ninterfacial\ndipole and suitable wettability are prerequisites for interlayer materials,\nin addition to the aligned energy level and high conductivity. However,\nthese have been rarely realized simultaneously in electron-transporting\nlayer (ETL) materials to date. Herein, an electron-transporting polymer,\nPPDIN-C6-F, by integrating the perylene diimide (PDI) segment and\nthe fluorinated alkyl spacer (C<sub>6</sub>F<sub>12</sub>) was synthesized\nvia a cost-effective quaternization polymerization reaction. Compared\nto the control polymer, PPDIN-C6-H, with the C<sub>6</sub>H<sub>12</sub> spacer, PPDIN-C6-F shows exceptional capabilities in film formation,\nself-doping, and electrical conductivity. When PPDIN-C6-F was used\nas the ETL in OSCs, decreased energy barrier and minimized interfacial\ndefects can be obtained. Consequently, PPDIN-C6-F demonstrated superior\ndevice performance, delivering a remarkable power conversion efficiency\n(PCE) up to 18.68% in PM6:L8-BO-based OSCs. Notably, the OSCs based\non PPDIN-C6-F ETL display excellent storage and thermal stability\nwith 91% and 79% of the initial PCEs maintained after aged for 1000\nand 600 h, respectively, which have decayed to 84% and 59% for those\nwith PPDIN-C6-H as ETL. Furthermore, its versatility is highlighted\nin OSCs with various photoactive layers, and a high PCE up to 19.20%\ncan be provided in the ternary PM6:SD-EDOT:L8-BO system.