Efficient Pure Blue Hyperfluorescence OLEDs with Donor-Acceptor-Donor Type Thermally Activated Delayed Fluorescence Sensitizer

In a hyperfluorescecne (HF) system, minimization of energy loss channel consisted of slow reverse intersystem crossing (RISC) and fast Dexter energy transfer (DET) is still challenging. Here, we report that such energy loss channels can minimize by utilizing quadrupolar donor-acceptor-donor (D-A-D) type TADF as sensitizer materials. We synthesized DBA-DmICz and DBA-DTMCz as D-A-D type TADF materials, which could suppress the DET process through fast RISC rate and shielded lowest unoccupied molecular orbital structure. The fabricated HF device with DBA-DTMCz and v-DABNA as a final dopant exhibited 43.9% of high maximum external quantum efficiency (EQEmax) with the CIE coordinates of (0.12, 0.16).