Aggregation-Induced Delayed Fluorescence Luminogens for Efficient Organic Light-Emitting Diodes.

Aggregation-induced delayed fluorescence (AIDF) can be regarded as a special case of aggregation-induced emission (AIE). Luminogens with AIDF can simultaneously emit strongly in solid state and fully utilize the singlet and triplet excitons in organic light-emitting diodes (OLEDs). In this work, two new AIDF luminogens, DMF-BP-DMAC and DPF-BP-DMAC, with an asymmetric D-A-D' structure, are designed and synthesized. The characteristics of both luminogens are systematically investigated, including single crystal structures, theoretical calculations, photophysical properties and thermal stabilities. Inspired by their AIDF nature, the green-emission non-doped OLEDs based on them are fabricated, which afford good electroluminescence performances, with low turn-on voltages of 2.8 V, high luminance of 52560 cd m-2 , high efficiencies of up to 14.4 %, 42.3 cd A-1 and 30.2 lm W-1 , and very small efficiency roll-off. The results strongly indicate the bright future of non-doped OLEDs on the basis of robust AIDF luminogens.