Over 18% Efficiency Ternary All-Polymer Solar Cells with High Photocurrent and Fill Factor

The superior photostability, excellent mechanical flexibility and stretchability enable all-polymer solar cells (all-PSCs) to be desirable for commercialization. Whereas, the efficiency of all-PSCs is still inferior to the small molecular acceptor (SMA) counterpart-based devices, which is mainly hampered by their relatively low short-circuit current density (Jsc) and fill factor (FF). Herein, we fabricated efficient ternary all-PSCs by introducing a fluorinated small molecular acceptor-derived polymer acceptor named PYF-T-o to broaden the absorption of the all-polymer blend and improve the molecular crystallinity. PYF-T-o was found to have a supreme compatibility with the host PY-DT acceptor, thus contributing to form a homogenous mixed-phase in the active layer. Consequently, the ternary all-PSC exhibits simultaneously improved Jsc and FF than those of the binary all-PSC, resulting in an impressive efficiency of 18.15% (certified as 17.73%), which is among the highest efficiency reported for all-PSCs thus far. Moreover, the large-area (1 cm2) and eco-friendly ternary all-PSCs (processed with o-xylene) were fabricated, and high efficiencies of 16.43% and 17.67% are obtained, respectively, showing the great potential of all-PSCs for future organic photovoltaic applications.