Heptazine‐Assisted Multi‐Resonance TADF Emitters With Fast Reverse Intersystem Crossing for Efficient Solution‐Processed OLEDs

ABSTRACT The development of solution‐processed organic light‐emitting diodes (SP‐OLEDs) with narrowband emission, high brightness, and minimal efficiency roll‐off remains a significant challenge. Herein, we report a series of heptazine‐assisted multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters for high‐performance SP‐OLEDs. By integrating a heptazine core with one to three MR units (tBuCzBN), we synthesized three emitters ( HAP‐CzBN , HAP‐2CzBN , and HAP‐3CzBN ) exhibiting excellent photoluminescence quantum yields and progressively reduced singlet–triplet energy gaps (Δ E ST ) with increasing MR content. Among these, HAP‐2CzBN and HAP‐3CzBN show green and yellow emission at 537 and…

• NS
  Natural Sciences and Engineering Research Council of Canada
• NM
  National Major Science and Technology Projects of China