Combination of heterojunction and mixed-host structures in one blue fluorescent organic light emitting diode to improve the power efficiency

High power efficiency blue organic light-emitting diode (OLED), based on 2-methyl-9,10-di(2-naphthyl) anthracene (MADN) and p-bis(p-N,N-diphenyl-amino-styryl) benzene (DSA-ph), has been realized by combining heterojunction (HJ) structure and mixed host (MH) structure in one device. This combination resulted in both high current efficiency and low driving voltage, and thus highly efficient blue OLED with peak power efficiency of 5.0 lm/W was achieved, which is approximately five times higher than 1.1 lm/W in the MH control device and 56% higher than 3.2 lm/W in the HJ control device.     

Efficient orange-red organic light-emitting diodes using 9,10-bis[4-(di-4-tert-butylphenylamino)styryl] anthracene as a fluorescent orange-red emitter

The authors have demonstrated efficient orange-red organic lighting diodes (OLEDs) using a new fluorescent orange-red material, 9,10-bis[4-(di-4-tert-buthylphenylamino)styryl]anthracene (ATBTPA). The optimized orange-red OLED using ATBTPA achieved a maximum external quantum efficiency (EQE) of 3.78%, a current efficiency (CE) of 9.47 cd/A, and Commision Internationale de L'Eclairage (CIE_x,y) coordinates of (0.51, and 0.48) at 1.61 mA/cm² in comparison with orange-red OLED using (5,6,11,12)-tetraphenyl-naphthacene (rubrene) which showed a maximum EQE of 1.65%, CE of 4.94 cd/A, and CIE_x,y coordinates of (0.50, and 0.49) at 0.61 mA/cm², respectively. The optimized orange-red device using ATBTPA showed higher efficiency of two times the orange-red device using rubrene due to the efficient Förster singlet energy transfer from MADN to ATBTPA in comparison with that from MADN to rubrene. This study clearly suggests that ATBTPA is an excellent fluorescent orange-red material for efficient WOLEDs.