Enhanced electroluminescence based on thermally activated delayed fluorescence from a carbazole-triazine derivative.

Physical chemistry chemical physics : PCCP

PubMedID: 23907636

Serevicius T, Nakagawa T, Kuo MC, Cheng SH, Wong KT, Chang CH, Kwong RC, Xia S, Adachi C. Enhanced electroluminescence based on thermally activated delayed fluorescence from a carbazole-triazine derivative. Phys Chem Chem Phys. 2013;.
Thermally activated delayed fluorescence (TADF) properties of a dicarbazole-triazine compound, 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-3,3'-bicarbazole (), and its OLED characteristics were investigated. An estimated small energy gap of about 90 meV between the singlet and triplet energy states of made the up-conversion of triplet excitons back to a singlet state possible. The origin of the observed delayed fluorescence has been shown to be thermally activated delayed fluorescence. An organic light emitting diode (OLED) with as an emitter showed the maximum external quantum efficiency (EQE) of 6%. For comparison, another carbazole-triazine derivative of 3-(2'-(4,6-diphenyl-1,3,5-triazin-2-yl)-[1,1'-biphenyl]-2-yl)-9-phenyl-9H-carbazole () with a similar structure was also studied. showed a low fluorescence quantum yield with no TADF.