High-efficiency single emissive layer color-tunable all-fluorescent white organic light-emitting diodes

This paper reports the high-efficiency single emissive layer of color-tunable white organic light-emitting diodes by precisely controlling the doping concentration of the two guest materials. The selection of host material with matched energy levels was more conducive to carrier transfer to the guests and effectively improved device electroluminescent (EL) performance. The stepwise energy levels of 4,4′,4″-tris(carbazole-9-yl)triphenylamine (TcTa), 9,10-bis[4-(6-methylbenzothiazol-2-yl)phenyl]anthracene (DBzA) and 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidn-4-yl-vinyl)-4H-pyran (DCJTB) doping and effective energy transfer between the host and guest enable the EL spectrum can be tuned with increasing voltage and the color temperature range coverage was significantly enhanced. When the doping concentrations of DBzA and DCJTB were determined to be 18 wt% and 0.4 wt%, the device exhibited a wide color temperature span from 2700 to 12104 K. The Commission Internationale de L’Eclairage (CIE) coordinates shifted from (0.470, 0.456) at 3 V to (0.281, 0.263) at 11 V, and the CIE coordinates closest to standard white light of (0.334, 0.329) were achieved at 6.3 V. Finally, the optimal device with the highest brightness of 30562 cd/m2, current efficiency of 22.83 cd/A, power efficiency of 26.6 lm/W, and color rendering index up to 81 was obtained.