Combining Charge‐Transfer Pathways to Achieve Unique Thermally Activated Delayed Fluorescence Emitters for High‐Performance Solution‐Processed, Non‐doped Blue OLEDs

Two efficient blue thermally activated delayed fluorescence compounds, B‐oCz and B‐oTC, composed of ortho‐donor (D)–acceptor (A) arrangement were designed and synthesized. The significant intramolecular D–A interactions induce a combined charge transfer pathway and thus achieve small ΔEST and high efficiencies. The concentration quenching can be effectively inhibited in films of these compounds. The blue non‐doped organic light emitting diodes (OLEDs) based on B‐oTC prepared from solution processes shows record‐high external quantum efficiency (EQE) of 19.1 %.