Achieving deep-blue color in diboron embedded multi-resonance thermally activated delayed-fluorescence emitter for narrowband oleds

We report three deep blue multiple resonant TADF emitters, m-ν-DABNA, 4F-ν-DABNA, and 4F-m-ν-DABNA by incorporating methyl groups and fluorine atoms in diboron based ν-DABNA core. The introduction of methyl groups and fluorine atoms resulted in bandgap enhancement by electron donating and electron withdrawing effects. All three emitter’s exhibit pure blue emissions with high photoluminescence quantum yield around ~90%, small ∆EST (≤ 0.07 eV) values, and fast reverse intersystem crossing rate (kRISC). Fabricated OLEDs with these emitters show excellent external quantum efficiency over 33%. Among three materials, 4F-ν-DABNA and 4F-m-ν-DABNA exhibit the CIE y coordinate of 0.08 and 0.06, respectively.