Aggregation-state engineering and emission switching in D–A–D′ AIEgens featuring dual emission, MCL and white electroluminescence. Issue 24 (21st May 2020) - Tan, Ji-Hua
Abstract : D–A–D′ AIEgens exhibit dual emission involving a blue TADF (monomer) and an orange TADF/RTP (dimer), which are switchable via aggregation-state engineering, and demonstrate high contrast MCL as well as white EL emission with high CRI. Abstract : Thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) have attracted much recent attention for their capabilities to utilize triplet excitons for emission. Herein, we demonstrate a strategy for switching between intermolecular TADF and RTP through rational structure modulation and crystal engineering with two newly designed organic AIEgens, namely (4-(9 H -carbazol-9-yl)phenyl) (dibenzo[ b, d ]thiophen-2-yl)methanone (CTM ) and (4-(3, 6-di- tert -butyl-9 H -carbazol-9-yl) phenyl) (dibenzo[ b, d ]thiophen-2-yl) methanone (tCTM ). Both materials exhibit intramolecular TADF and intermolecular TADF/RTP dual emission in single crystals. High contrast mechanochromic luminescence (MCL) was unveiled due to the polymorphism of both emitters in aggregated states. Using these materials as emitters, we demonstrate for the first time, such dual TADF–TADF/RTP emissions can be exploited to obtain white light organic light-emitting diodes with high color rendering indexes.