AIE-active Circularly Polarized Thermally Activated Delayed Fluorescence Emitters for Stable Solution-Processed Circularly Polarized Electroluminescence

Circularly polarized organic light-emitting diodes (CP-OLEDs) have significant promise for naked-eye 3D displays. However, most devices are fabricated using vacuum deposition technology, and development of efficient solution-processed CP-OLEDs, particularly those exhibiting low efficiency roll-off, remains a formidable challenge. This research successfully designed and synthesized two pairs of thermally activated delayed fluorescence (TADF) enantiomers through isomer engineering, namely (R/S)-N-5-TPA and (R/S)-N-4-TPA, which features fifth and fourth substitution sites of phthalimide (acceptor) by tri-phenylamine (donor), respectively. Both molecules displayed aggregation-induced emission (AIE) properties. Notably, the CP-OLED devices, fabricated by solution-process, exhibited vivid blue-green and green emission with the maximum current efficiency of 7.4 and 29.6 cd A-1, the external quantum efficiency of 2.7% and 10.2%, and the low efficiency roll-off of 3.7% and 16.7%. Moreover, these devices demonstrated CP-EL signals with gEL values of +6.61 × 10-4 /-6.84 × 10-4 and +1.13 × 10-3/-1.25 × 10-3, respectively.