Versatile Thermally Activated Delayed Fluorescence Material Enabling High Efficiencies in both Photodynamic Therapy and Deep-Red/NIR Electroluminescence.

Abstract

Thermally activated delayed fluorescence (TADF) materials have received increasing attention from organic electronics to other related fields, such as bioapplications and photocatalysts. However, it remains a challenging task for TADF emitters to showcase the versatility concurrent with high performance in multiple applications. Herein, we first present such a proof-of-concept TADF material, namely, QCN-SAC, through strategically manipulating exciton dynamics. On the one hand, QCN-SAC displays obvious aggregate-induced deep-red/near-infrared emission with a high radiative rate beyond 10⁷ s^-1, thereby demonstrating nearly 100% exciton utilization under oxygen-free conditions. In a QCN-SAC-based nondoped organic light-emitting diode (OLED), a superb external quantum efficiency of 16.4% can be reached with a peak at 708 nm. On the other hand, QCN-SAC also exhibits a high intersystem crossing rate over 10⁸ s^-1 without leveraging the heavy-atom effect, which makes QCN-SAC-based nanoparticles perform well in boosting reactive oxygen species generation for imaging-guided photodynamic therapy (PDT). This work presents a fundamental principle for designing high-performance all-in-one TADF molecules for OLED and PDT applications. This discovery holds promise for advancing the development of versatile TADF materials with a range of uses in the near future.