Efficient solution processed hybrid white organic light-emitting diodes based on a blue thermally activated delayed fluorescence emitter

Abstract

A solution-processed blue thermally activated delayed fluorescence (TADF) aromatic molecule has been introduced to realize high-efficiency hybrid white organic light-emitting diodes (WOLEDs) with very simple structure which contains only three organic layers of hole injection layer, emissive layer (EML), and electron transporting layer. 1,3-Bis(N-carbazolyl)benzene doped with the blue TADF molecule 10-(4-(4,6-diphenyl 1,3,5 triazin-2-yl)-2-methylphenyl)-10H-spiro[acridine-9,9'-fluorene] was mixed with a red phosphorescent emitter, bis(2-methyldibenzo [th]quinoxaline) (acetylacetonate) iridium(III) to form a blue-red fluorescent-phosphorescent hybrid EML. The resultant hybrid EML was applied to construct a solution-processed WOLEDs. Hence, a maximum external quantum efficiency of 11.02% and current efficiency of 22.46 cd/A with the Commission Internationale de L'Eclairage coordinates of (0.43, 0.40) were achieved by co-doping of blue and red emitters in a single layer.