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

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, pMDBA-DI and mMDBA-DI, and a pure blue multi-resonance type tert-butyl substituted TADF fluorescence emitter t-Bu-nu-DABNA are reported, for efficient HF devices. Among the synthesized TADF sensitized host materials, the mMDBA-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-nu-DABNA with efficient Forster energy transfer.