Complementary Multi‐Resonance Thermally Activated Delayed Fluorescence Design for Blue OLEDs Beyond the Concentration Limit

Abstract Advances in boron‐based organic compounds exhibiting multi‐resonance (MR)‐type thermally activated delayed fluorescence (TADF) have been primarily driven by their potential as narrowband blue emitters for wide‐gamut display applications. Nevertheless, the intrinsically planar architecture of MR‐type TADF molecules often leads to pronounced concentration quenching at elevated doping levels, posing a significant impediment to realizing highly efficient organic light‐emitting diodes (OLEDs). Notably, the exciton quenching effect observed here fundamentally follows the same energy transfer mechanism that underlies exciton migration. Based on this insight, we developed a system comprising two MR‐TADF molecules with analogous electronic structures that enable mutual exciton energy transfer. The resultant complementary MR‐TADF emitter system exhibits substantially improved resistance to concentration quenching relative to single MR‐TADF emitters, effectively suppressing efficiency drop and conferring enhanced control over exciton density. We envisage that this strategy represents a pivotal step toward overcoming the longstanding challenge of concentration quenching in MR‐TADF materials, thereby enabling the development of high‐performance deep‐blue OLEDs.