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.