A bipolar host containing carbazole/dibenzothiophene for efficient solution-processed blue and white phosphorescent OLEDs

The photophysical properties of a novel small molecule host containing carbazole/dibenzothiophene (CzDBS) were studied. Solution processing of CzDBS found well-balanced bipolar functionalities, high triplet bandgap, and good thin-film morphology. By using this compound as a host material, high-performance solution-processed blue and white phosphorescent organic light emitting devices were fabricated. The blue and white emitting devices showed maximum efficiencies, with 13.9% external quantum efficiency (EQE), 29.7 cd A(-1) CE, 18.6 lm W-1 PE and 13.8% EQE, 29.1 cd A(-1) CE, and 17.7 lm W-1 PE, respectively. In addition, through incorporation of the light-extraction structures, white-light emission with the Commission Internationale de l'Eclairage chromaticity coordinates (0.38, 0.40) and satisfactory efficiencies of 22.9% EQE, 48.4 cd A(-1) CE, and 30.4 lm W-1 PE were demonstrated.