P‐181: Efficient Thermally Activated Delayed Fluorescence Sensitizer of Hyperfluorescence OLED by Adding Blocking Group

In this work, two thermally activated delayed fluorescence (TADF) materials, TrzCN and t‐TrzCN were synthesized to study effect of blocking group at acceptor unit in yellow hyperfluorescence system Two TADF materials were designed to prevent Dexter energy transfer by integrating t‐butyl substituted triazine, nitrile electron withdrawing unit and diindolocarbazole electron donating unit. By comparing these two materials, we could confirm the effect of blocking group. In 20% TADF and 0.5% TBRb doped devices, TrzCN TADF sensitizer without t‐butyl group material with TBRb fluorescence device showed maximum external quantum efficiency of 15.8%. The t‐TrzCN TADF sensitizer with t‐butyl group material showed maximum external quantum efficiency 17.6%.