10.13% Efficiency Alla??Polymer Solar Cells Enabled by Improving the Optical Absorption of Polymer Acceptors

摘要： All-polymer solar cells (all-PSCs) are one of the most promising flexible and wearable energy generators due to their excellent morphology stability and mechanical robustness. However, it has been limited light absorption capacity for most polymer acceptors that hinders the improvement of power conversion efficiency (PCE) of all-PSCs. Herein, by simultaneously increasing the conjugation of the acceptor unit and enhancing the electron-donating ability of the donor unit, a novel narrow-bandgap polymer acceptor PF3-DTCO based on a A-D-A-structured acceptor unit ITIC16 and a carbon-oxygen (C-O)-bridged donor unit DTCO was developed. Extended conjugation of the acceptor units from IDIC16 to ITIC16 result in a red-shifted absorption spectrum and improved absorption coefficient without significant LUMO level reduction. Moreover, in addition to further broadening the absorption spectrum by the enhanced intramolecular charge transfer effect, the introduction of C-O-bridges into donor unit improves the absorption coefficient and electron-mobility, as well as optimizes the morphology and molecular order of active layers. As a result, the PF3-DTCO achieved a higher PCE of 10.13% with a higher short-circuit current density (Jsc) of 15.75 mA cm-2 in all-PSCs compared to its original polymer acceptor PF2-DTC (PCE=8.95% and Jsc=13.82 mA cm-2). Our work provides a promising method to construct high-performance polymer acceptors with excellent optical absorption for efficient all-PSCs.