Aggregation-induced emission luminogen in ternary organic bulk-heterojunction for efficient perovskite-organic tandem...

Perovskite-organic tandem solar cells (TSCs) have recently garnered significant attention due to their potential for high power conversion efficiency (PCE) and excellent stability. However, their development has been significantly hindered by the large open-circuit voltage (V_OC) deficit in organic sub-cells, primarily caused by severe non-radiative recombination, which is closely related to the electroluminescence quantum efficiency (EQE_EL) and the photoluminescence quantum yield (PLQY). However, mainstream non-fullerene molecules exhibit low PLQY due to the aggregation-caused quenching (ACQ) effect. In this study, an aggregation-induced emission (AIE)-active molecule (TPE-BTA3) featuring a three-dimensional rotor-stereo configuration is rationally designed with an exceptional PLQY of 68%. When TPE-BTA3 is introduced into binary Organic solar cells (OSCs), it not only dramatically enhances the PLQY of alloy-acceptor but also strengthens the utilization of near-infrared photons, leading to a significant increase in V_OC and short-circuit current (J_SC). By integrated above optimized ternary organic bulk-heterojunction with a wide-bandgap (1.85 eV) perovskite, the constructed perovskite-organic TSCs achieve a surprising PCE of 26.5% (certified as 25.8%). This work establishes a conceptual bridge between high-efficiency photovoltaics and AIE molecular design paradigms.