Highly Efficient Green and Red Narrowband Emissive Organic Light-Emitting Diodes Employing Multi-Resonant Thermally Activated Delayed Fluorescence Emitters

Herein, we demonstrate how judicious selection of the donor decorating a central multi-resonant thermally activated delayed fluorescence (MR-TADF) core based on DiKTa can lead to very high-performance OLEDs. By decorating the DiKTa core with triphenylamine (TPA) and diphenylamine (DPA), 3TPA-DiKTa and 3DPA-DiKTa exhibit bright, narrowband green and red emission in doped films, respectively. The OLEDs based on these emitters showed record-high performance for this family of emitters with maximum external quantum efficiencies (EQE(max)) of 30.8% for 3TPA-DiKTa at lambda (EL) of 551nm and 16.7% for 3DPA-DiKTa at lambda (EL)=613nm. The efficiency roll-off in the OLEDs was improved significantly by using 4CzIPN as an assistant dopant in hyperfluorescence (HF) devices. The outstanding device performance has been attributed to preferential horizontal orientation of the transition dipole moments of 3TPA-DiKTa and 3DPA-DiKTa.

Automated summary

In this study, we demonstrate the method of improving OLED performance by carefully selecting the donor. By decorating the DiKTa core with TPA and DPA, we achieved bright and narrowband green and red emission, respectively. The OLEDs based on these emitters showed outstanding performance with the highest external quantum efficiencies.