As one of the three primary colors indispensable for full-color displays, the development of blue emitters is of great importance and still a difficult challenge for organic light-emitting diodes (OLEDs). Blue organic emitters exhibiting thermally activated delayed fluorescence (TADF) are anticipated to be promising materials as they have the potential to achieve high electroluminescence (EL) efficiencies and suitable color purity. In this paper, highly efficient blue TADF emitters combining 1,8-dimethylcarbazole as a weak donor (D) unit with a triazine-based acceptor (A) core are reported. Unlike unsubstituted carbazole, 1,8-dimethylcarbazole can effectively induce intermolecular twisting between the D-A linkages, thus enhancing the TADF properties. Moreover, a quadrupolar D-A-D-type blue TADF emitter exhibits superior photo- and electroluminescence (EL) properties compared to a dipolar D-A-type counterpart. TADF-OLEDs based on the D-A-D-type emitter featuring the 1,8-dimethylcarbazole−triazine conjugates display a brilliant blue EL emission and furnish a maximum external EL quantum efficiency as high as 21.2 % with CIE color coordinates of (0.16, 0.27).
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Analytical Chemistry