Professor Kyung Hee University Seoul, Republic of Korea
We report three deep blue multiple resonant TADF emitters, m-?-DABNA, 4F-?-DABNA, and 4F-m-?-DABNA by incorporating methyl groups and fluorine atoms in diboron based ?-DABNA core. The introduction of methyl groups and fluorine atoms resulted in bandgap enhancement by electron-donating and electron-withdrawing effects. All three emitters 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 of over 33%. Among three materials, 4F-?-DABNA and 4F-m-?-DABNA exhibit the CIE y coordinate of 0.08 and 0.06, respectively.
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