High‐Performance Ternary Organic Solar Cells Enabled by Integrating a 3D‐Shaped Guest Acceptor Derived from Perylene Diimide

Abstract Integrating a third component into the binary system is considered to be one of the most effective strategies to further enhance the power conversion efficiency (PCE) in organic solar cells (OSCs). Here, a novel perylene diimide (PDI) derivative featuring 3D structure, TPA‐4PDI, with tetraphenyladamantane central core is developed as a guest electron acceptor to be incorporated into the PM6:Y6 binary system. The champion PCE of ternary OSC is recorded to be 18.29% by adding 7.5 wt.% of TPA‐4PDI in the ternary blend, which photovoltaic performance is enhanced with synergistically increased open‐circuit voltage (V_oc) of 0.849 V, short‐circuit current density (J_sc) of 27.55 mA cm⁻², and fill factor (FF) of 78.21%. TPA‐4PDI exhibits a complementary absorption band with PM6 and Y6 while its lowest unoccupied molecular orbital (LUMO) energy level falls between the two host materials. The addition of TPA‐4PDI can effectively suppress the recombination behavior, inhibit the excessive aggregation of Y6 and improve the morphology of PM6:Y6 blend. All these effects function synergistically and then lead to the enhancement of V_oc, J_sc, and FF in ternary OSCs. This study suggests that developing PDI derivatives as the third component is an effective method to further improve the performance of ternary OSCs.