Triptycene‐Derived 3D‐Architectured Non‐fullerene Acceptor with High Luminescence Enables 20.26% Efficiency Organic Solar Cells

Developing narrow-bandgap nonfullerene acceptors (NFAs) with high photoluminescence quantum yield (PLQY) is a major challenge, but also a promising strategy to reduce nonradiative energy loss for boosting power-conversion-efficiency (PCE) of organic solar cells (OSCs). Herein, we design and synthesize a Y-series NFA (Y-NFA, named TQX-IC) by incorporating a triptycene-derived "highly luminescent" and "3D-architectured" substituent. Study shows that TQX-IC can suppress aggregation-caused quenching (ACQ), achieving a remarkable PLQY of 12.80%, currently one of the highest reported values among Y-NFAs. Therefore, its binary OSCs offer an exceptionally low nonradiative energy loss of 0.148 eV, significantly outperforming the control Y-NFA named Me-Y (0.209 eV). When incorporating it as a third component into D18:BTP-eC9 and D18:L8-BO systems, ternary OSCs based on both D18:BTP-eC9:TQX-IC and D18:L8-BO:TQX-IC achieve impressive PCEs of 19.48% and 20.26%, respectively, significantly surpassing the Me-Y based ternary OSCs (18.19% and 18.23%). This enhancement of ternary systems is attributed to the reduced nonradiative energy loss, optimized exciton dynamics, improved charge transport, and optimized active layer morphology and component distribution when compared to their binary systems. Our findings demonstrate that introducing "highly luminescent" and "3D-architectured" substituent into Y-NFAs is a promising approach to enhance PLQY, thereby paving the way toward efficient OSCs.