Interlayer Engineering with Different Host Material Properties in Blue Phosphorescent Organic Light-Emitting Diodes

ETRI Journal

关键词: interlayer;    phosphorescent;    blue;    Organic light-emitting diodes (OLED);   

Others  :  1186155
DOI  :  10.4218/etrij.11.0110.0172

【 摘 要 】

We investigated the light-emitting performances of blue phosphorescent organic light-emitting diodes, known as PHOLEDs, by incorporating an N,N′-dicarbazolyl-3,5-benzen interlayer between the hole transporting layer and emitting layer (EML). We found that the effects of the introduced interlayer for triplet exciton confinement and hole/electron balance in the EML were exceptionally dependent on the host materials: 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole, 9-(4-tert-butylphenyl)-3,6-ditrityl-9H-carbazole, and 4,4′-bis-triphenylsilanyl-biphenyl. When an appropriate interlayer and host material were combined, the peak external quantum efficiency was greatly enhanced by over 21 times from0.79% to 17.1%. Studies on the recombination zone using a series of host materials were also conducted.

   

【 参考文献 】

• [1]B.W. D’Andrade and S.R. Forrest, "White Organic Light-Emitting Devices for Solid-State Lighting," Adv. Mater., vol. 16, no. 18, 2004, pp. 1585-1595.
• [2]K.T. Kamtekar, A.P. Monkman, and M.R. Bryce, "Recent Advances in White Organic Light-Emitting Materials and Devices (WOLEDs)," Adv. Mater., vol. 22, no. 5, 2010, pp. 572-582.
• [3]S. Reineke et al., "White Organic Light-Emitting Diodes with Fluorescent Tube Efficiency," Nature, vol. 459, 2009, pp. 234-239.
• [4]J. Lee, J.I. Lee, and H.Y. Chu, "Improved Performance of White Phosphorescent Organic Light-Emitting Diodes through a Mixed-Host Structure," ETRI. J., vol. 31, no. 6, 2009, pp. 642-646.
• [5]J. Lee, J.I. Lee, and H.Y. Chu, "Efficient and Color Stable Phosphorescent White Organic Light-Emitting Devices based on an Ultra Wide Band-Gap Host," Synth. Met., vol. 159, no. 11, 2009, pp. 991-994.
• [6]C. Adachi et al., "Nearly 100% Internal Phosphorescence Efficiency in an Organic Light Emitting Device," J. Appl. Phys., vol. 90, 2001, pp. 5048-5051.
• [7]C. Adachi et al., "Endothermic Energy Transfer: A Mechanism for Generating Very Efficient High-Energy Phosphorescent Emission in Organic Materials," Appl. Phys. Lett., vol. 79, 2001, pp. 2082-2084.
• [8]H. Inomata et al., "High-Efficiency Organic Electrophosphorescent Diodes Using 1, 3, 5-Triazine Electron Transport Materials," Chem. Mater., vol. 16, 2004, pp. 1285-1291.
• [9]S.J. Su et al., "Pyridine-Containing Bipolar Host Materials for Highly Efficient Blue Phosphorescent OLEDs," Chem. Mater., vol. 20, 2008, pp. 1691-1693.
• [10]R.J. Holmes et al., "Efficient, Deep-Blue Organic Electrophosphorescence by Guest Charge Trapping," Appl. Phys. Lett., vol. 83, 2003, pp. 3818-3820
• [11]M.H. Tsai et al., "Triphenylsilyl- and Trityl-Substituted Carbazole-Based Host Materials for Blue Electrophosphorescence," ACS Appl. Matter. Interfaces, vol. 1, 2009, pp. 567-574.
• [12]J.J. Lin et al., "A Highly Efficient Host/Dopant Combination for Blue Organic Electrophosphorescence Devices," Adv. Funct. Matter., vol. 18, 2008, pp. 485-491.
• [13]S.J. Su et al., "Highly Efficient Organic Blue- and White-Light-Emitting Devices Having a Carrier- and Exciton-Confining Structure for Reduced Efficiency Roll-Off," Adv. Matter., vol. 20, 2008, pp. 4189-4194.
• [14]J. Lee, J.I. Lee, and H.Y. Chu, "Investigation of Double Emissive Layer Structures on Phosphorescent Blue Organic Light-Emitting Diodes," Synth. Met., vol. 159, 2009, pp. 1460-1463.
• [15]J. Lee et al., "Influence of Doping Profile on the Efficiency of Blue Phosphorescent Organic Light-Emitting Diodes," Appl. Phys. Lett., vol. 92, 2008, pp. 133304-1-3.
• [16]S.H. Eom et al., "Low Voltage and Very High Efficiency Deep-Blue Phosphorescent Organic Light-Emitting Devices," Appl. Phys. Lett., vol. 93, 2008, pp. 133309-1-3.
• [17]J. Lee et al., "Enhanced Efficiency and Rreduced Roll-Off in Blue and White Phosphorescent Organic Light-Emitting Diodes with a Mixed Host Structure," Appl. Phys. Lett., vol. 94, 2009, pp. 193305-1-3.
• [18]J. Lee et al., "Improved Performance of Blue Phosphorescent Organic Light-Emitting Diodes with a Mixed Host System," Appl. Phys. Lett., vol. 95, 2009, pp. 253304-1-3.
• [19]J. Lee et al., "Effects of Interlayers on Phosphorescent Blue Organic Light-Emitting Diodes," Appl. Phys. Lett., vol. 92, 2008, pp. 203305-1-3.
• [20]S.O. Jeon et al., "High Efficiency Blue Phosphorescent Organic Light Emitting Diodes Using a Simple Device Structure," Appl. Phys. Lett., vol. 94, 2009, pp. 013301-1-3.
• [21]J. Lee et al., "Stable Efficiency Roll-Off in Blue Phosphorescent Organic Light-Emitting Diodes by Host Layer Engineering," Org. Electron., vol. 10, 2009, pp. 1529-1533.
• [22]S.H. Kim, J. Jang, and J.Y. Lee, "High Efficiency Phosphorescent Organic Light-Emitting Diodes using Carbazole-type Triplet Exciton Blocking Layer," Appl. Phys. Lett., vol. 90, 2007, pp. 223505-1-3.
• [23]V.I. Adamovich et al., "New Charge-Carrier Blocking Materials for High Efficiency OLEDs," Org. Electron., vol. 4, 2003, pp. 77-87.
• [24]H. Aziz, Z.D. Popovic, and N.X. Hu, "Organic Light Emitting Devices with Enhanced Operational Stability at Elevated Temperatures," Appl. Phys. Lett., vol. 81, 2002, pp. 370-372.
• [25]E. Polikarpov et al., "Emission Zone Control in Blue Organic Electrophosphorescent Devices through Chemical Modification of Host Materials," Appl. Phys. Lett., vol. 96, 2010, pp. 053306-1-3.