Different configurations of phosphorescent yellow emissive layer in white organic light-emitting device

We fabricated white organic light-emitting devices (WOLEDs) based on three different configurations for yellow emissive layer (Y-EML), using phosphorescent yellow bis[2-(4-tert-butylphenyl)benzothiazolato-N,C2’]iridium (acetylacetonate) [(t-bt)2Ir(acac)]. The Y-EML was formed as undoped ultrathin layer, doped ultrathin layer with low (tbt) 2Ir(acac) concentration and doped thin layer with the same amount of (t-bt)2Ir(acac) molecular as the undoped YEML. The results showed that the difference in configurations of the Y-EML affected not only the operating voltage but also the luminance and efficiency characteristics of the devices. Comparing device performance, it was found that devices based on the doped Y-EML showed low efficiency and yellow-dominated light emission, due to triplet exciton hopping caused by different triplet energy. On the other hand, a device with the undoped Y-EML demonstrated the highest efficiency (79.0 cd/A at 1 550 cd/m2 and 40.5 lm/W at 1 000 cd/m2), attributing to well confined charge carriers and excitons.

[1]  Jun Yeob Lee,et al.  High efficiency and low efficiency roll off in white phosphorescent organic light-emitting diodes by managing host structures , 2008 .

[2]  Q. Gong,et al.  Undoped yellow-emitting organic light-emitting diodes from a phenothiazine-based derivative , 2007 .

[3]  Junsheng Yu,et al.  Low roll-off power efficiency organic light-emitting diodes consisted of nondoped ultrathin phosphorescent layer , 2008 .

[4]  Junsheng Yu,et al.  High-efficiency white organic light-emitting devices with a non-doped yellow phosphorescent emissive layer , 2012 .

[5]  Junsheng Yu,et al.  High-efficiency White Phosphorescent Organic Light-Emitting Diodes , 2007 .

[6]  Martin Pfeiffer,et al.  Highly efficient top emitting organic light-emitting diodes with organic outcoupling enhancement layers , 2006 .

[7]  Masanori Ozaki,et al.  Organic electroluminescent diodes as a light source for polymeric integrated devices , 2001, SPIE OPTO.

[8]  Junsheng Yu,et al.  Efficient white organic light-emitting devices using a thin 4,4′-bis(2,2′-diphenylvinyl)-1,1′-diphenyl layer , 2008 .

[9]  Zhuozhi Wang,et al.  Highly simplified phosphorescent organic light emitting diode with >20% external quantum efficiency at >10,000 cd/m2 , 2011 .

[10]  Yanfeng Dai,et al.  Improved performances of organic light-emitting diodes with metal oxide as anode buffer , 2007 .

[11]  C. Tang,et al.  Organic Electroluminescent Diodes , 1987 .

[12]  S. Forrest,et al.  Highly efficient phosphorescent emission from organic electroluminescent devices , 1998, Nature.

[13]  Stephen R. Forrest,et al.  Transient analysis of organic electrophosphorescence. II. Transient analysis of triplet-triplet annihilation , 2000 .