▎ 摘　　要

A strategy to enhance the carboxyl content of graphene oxide (GO) is proposed. By creating defects to obtain new edge sites on GO, the carboxyl content of the new derivative d-GO-COOH is increased from an initial 3.06% to 9.08% (at.%), while the other oxygen-containing functional groups are less than that of GO. After loading the carboxyl group with cesium (Cs), the obtained d-GO-COOCs had a higher Cs content of 6.05% (at.%). Hence a lower work function (4.14 eV) is realized compared to that of GO-COOCs (4.37 eV). The cathode interface layer (CIL) effect of d-GO-COOCs was studied in inverted organic solar cells (OSCs). A new small molecule i-IEICO-Br was designed and prepared as the electron-acceptor to match with the wide bandgap polymer donor materials (PBDB-T). In contrast to GO-COOCs-based devices, the open-circuit voltage (VOC), short-circuit current density (JSC), and fill factor (FF) of d-GO-COOCs-based devices were simultaneously improved, giving the higher power conversion efficiency (PCE) of 6.10%. The enhanced CIL characteristic of d-GO-COOCs was further confirmed in the PM6:Y6 material system. These results imply that through selective structural optimization, GO could be better adapted to the application in OSCs and would contribute to the wider use of GO-based CIL.