Concentration quenching–resistant multiresonance thermally activated delayed fluorescence emitters

Abstract A deep blue thermally activated delayed fluorescence (TADF) organic light-emitting diode resistant to the concentration quenching effect was developed using a multiresonance-type boron emitter decorated with a di(tert-butylphenyl)amine unit. The di(tert-butylphenyl)amine group surrounding the rigid core structure enabled a high photoluminescence quantum yield and fast reverse intersystem crossing of the multiresonance TADF emitter even at high doping concentrations. The multiresonance B–N type blue TADF emitter showed narrow blue emission spectrum with a full width at half maximum of 25 nm without bathochromic shift by the additional donor. It showed a high external quantum efficiency of more than 26%, a deep blue emission color of (0.13, 0.08), and a very small efficiency decrease of 2% even at high doping concentrations.