Over 18% efficiency ternary all-polymer solar cells with high photocurrent and fill factor

Limited by the relatively low short-circuit current density (J_sc) and fill factor (FF), the efficiency of all-polymer solar cells (all-PSCs) is still inferior to the small molecular acceptor (SMA) counterpart-based devices. Herein, we fabricate 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 good compatibility with the host PY-DT acceptor, thus contributing to form a homogeneous mixed phase in the active layer. Consequently, the ternary all-PSC exhibits simultaneously improved J_sc and FF than those of the binary all-PSC, resulting in an impressive efficiency of 18.15% (certified as 17.73%). 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% were obtained, respectively, showing the great potential of all-PSCs for future organic photovoltaic applications.