Pyrene‐Fused Perylene Diimides: New Building Blocks to Construct Non‐Fullerene Acceptors With Extremely High Open‐Circuit Voltages up to 1.26 V

Great efforts have been devoted to seeking alternative non‐fullerene acceptors for efficient polymer solar cells (PSCs). Achieving a high open‐circuit voltage ( V oc ) is quite challenging but is essential for practical application. Here, pyrene‐fused perylene diimide was first used as a periphery building block to construct non‐fullerene acceptors. Due to the high‐lying lowest unoccupied molecular orbitals (LUMOs) as well as balanced transport properties, the normal devices with the acceptors exhibited ultrahigh V oc values of up to 1.26 V. In addition, the achieved power‐conversion efficiency (PCE) of 5.10% is among the highest values for non‐fullerene PSCs with a V oc  > 1.20 V, indicating that the pyrene‐fused perylene diimide (PDI) unit is a useful building block for the design of non‐fullerene PSCs with high V oc values. This study could benefit the realization of both a high PCE and V oc in PSCs.