Achieving High Efficiency and Pure Blue Color in Hyperfluorescence Organic Light Emitting Diodes using Organo‐Boron Based Emitters

Abstract In the field of organic light‐emitting diodes, organo‐boron based thermally activated delayed fluorescence (TADF) emitters have witnessed outstanding achievements. However, it is still challenging to achieve pure blue color (CIE y < 0.20) along with high efficiencies. To overcome these hurdles, the hyperfluorescence (HF) system suggests a key strategy for future display applications. Here, two TADF host materials, p MDBA‐DI and m MDBA‐DI, and a pure blue multi‐resonance type tert‐butyl substituted TADF fluorescence emitter t ‐Bu‐ν‐DABNA are reported, for efficient HF devices. Among the synthesized TADF sensitized host materials, the m MDBA‐DI HF device exhibits a high external quantum efficiency of 39.1% along with narrow emission with full width at half maximum of 19 nm (CIE y = 0.15). The high device efficiency is mainly attributed to the high molecular orientation factor, enhanced photoluminescence quantum yield, and a good TADF characteristic of t ‐Bu‐ν‐DABNA with efficient Förster energy transfer.