Acta Phys. -Chim. Sin. ›› 2007, Vol. 23 ›› Issue (10): 1493-1497.doi: 10.1016/S1872-1508(07)60074-6

• ARTICLE • Previous Articles     Next Articles

High-efficiency of White Phosphorescent Organic Light-Emitting Diodes

LI Lu; YU Jun-Sheng; WANG Jun; LOU Shuang-Ling; JIANG Ya-Dong; LI Wei   

  1. State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054, P. R. China
  • Received:2007-04-05 Revised:2007-06-19 Published:2007-10-01
  • Contact: YU Jun-Sheng;JIANG Ya-Dong;

Abstract: High-efficiency white organic light-emitting devices (WOLEDs) based on phosphorescent dye bis[2-(4-tert-butylphenyl)benzothiazolato-N,C2’]iridium (acetylacetonate) [(t-bt)2Ir (acac)] doped 4,4’-bis (carbazol-9-yl) biphenyl (CBP) as a yellow emitting layer were fabricated. The structure of the devices is indium tin oxide (ITO)/N,N’-bis-(1-naphthyl)-N,N’-biphenyl-1,1’-biphenyl-4,4’-diamine (NPB)/CBP: (t-bt)2Ir(acac)/NPB/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/8-hydroxyquinoline aluminum(Alq3)/Mg:Ag, and the second NPB layer fromthe anode was used as a blue fluorescent emitter and the first NPB layer was used as a hole transporting layer, the BCP and Alq3 were used as hole blocking and electron transporting layers, respectively. The turn-on voltage of the device was 3 V with a maximumluminance of 15460 cd·m-2 at 16.5 V and maximumluminance efficiency of 7.5 lm·W-1 at 4 V, respectively. The Commission Internationale de I’Eclairage (CIE) coordinates located at (0.33, 0.32) remained stable at the driving voltage higher than 8 V, which is almost consistent with the optimum white CIE of (0.33, 0.33). The purity of white light could be adjusted by doping concentration. The effect of charge carrier trapping and energy transfer on the device performance were also discussed.

Key words: Organic light-emitting diodes, White light, Phosphorescence, Iridium complex, Carrier trapping, Energy transfer


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