Browse > Article
http://dx.doi.org/10.4313/JKEM.2009.22.6.512

Electrical and Optical Properties of Partially Doped Blue Phosphorescent OLEOs  

Seo, Yu-Seok (순천향대학교 신소재공학과)
Moon, Dae-Gyu (순천향대학교 신소재공학과)
Publication Information
Journal of the Korean Institute of Electrical and Electronic Material Engineers / v.22, no.6, 2009 , pp. 512-515 More about this Journal
Abstract
We have fabricated blue phosphorescent organic light emitting diodes (PHOLEDs) using a 3,5'-N,N'-dicarbazole-benzene (mCP) host and iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,$C^{2] picolinate (Flrpic) guest materials, The Flrpic was partially doped into the mCP host layer, for investigating recombination zone, current efficiency, and emission characteristics of the blue PHOLEDs. The recombination of electrons and holes takes place inside the mCP layer adjacent to the mCP/hole blocking layer interface. The best current efficiency was obtained in a device with an emission layer structure of mCP (10 nm)/mCP:Flrpic (20 nm, 10%). The high current efficiency in this device was attributed to the confinement of Ffrpic triplet excitons by the undoped mCP layer with high triplet energy, which blocks diffusion of Ffrpic excitons to the adjacent hole transport layer with a lower triplet energy.
Keywords
OLEO; Blue phosphorescent; Flrpic; Recombination zone; Energy confinement;
Citations & Related Records
Times Cited By KSCI : 1  (Citation Analysis)
연도 인용수 순위
1 J. Li, P. I. Djurovich, B. D. Alleyne, I. Tsyba, N. N. Ho, R. Bau, and M. E. Thompson, 'Synthesis and characterization of cyclometalated Ir(III) complexes with pyrazolyl ancillary ligands', Polyhedron, Vol. 23, p. 419, 2004   DOI   ScienceOn
2 R. J. Holmes, S. R. Forrest, Y.-J. Tung, R. C. Kwong, J. J. Brown, S. Garon, M. E. Thompson, 'Blue organic electro-phospho- rescence using exothermic host-guest energy transfer', Appl. Phys. Lett., Vol. 82, p. 2422. 2003   DOI   ScienceOn
3 J. W. Lee, N. Chopra, S.-H. Eom, Y. Zheng, J. Xue, F. So, and J. Shi, 'Effects of triplet energies and transporting properties of carrier transporting materials on blue phosphorescent organic light emitting devices', Appl. Phys. Lett., Vol. 93, p. 123306, 2003   DOI   ScienceOn
4 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, p. 223505, 2007   DOI   ScienceOn
5 M. E. Thompson and S. R. Forrest, 'Highly efficient phosphorescent emission from organic electroluminescent devices', Nature London, Vol. 395, p. 151, 1998   DOI   ScienceOn
6 Adachi, M. A. Baldo, M. E. Thompson, and S. R. Forrest, 'Nearly 100 % internal phosphorescence efficiency in an organic light- emitting device', J. Appl. Phys., Vol. 90, p. 5048, 2001   DOI   ScienceOn
7 서지현, '혼합된 정공 수송 층을 이용한 유기발광소자의 효율 및 수명 개선', 전기전자재료학회논문지, 20권, 3호, p. 257, 2007   DOI
8 K. Goushi, R. Kwong, J. J. Brown, H. Sasabe, and C. Adachi, 'Triplet exciton confinement and unconfinement by adjacent hole-transport layers', J. Appl. Phys., Vol. 95, p. 7798, 2004   DOI   ScienceOn
9 J. Holmes, S. R. Forrest, T. Sajoto, A. Tamayo, P. I. Djurovich, M. E. Thompson, J. Brooks, Y. J. Tung, B. W. D Andrade, M. S. Weaver, R. C. Kwong, and J. J. Brown, 'Saturated deep blue organic electrophosphorescence using a fluorine-free emitter', Appl. Phys. Lett., Vol. 87, p. 243507, 2005   DOI   ScienceOn
10 S. Tokito, T. Iijima, Y. Suzuri, H. Kita, T. Tsuzuki, and F. Sato, 'Confinement of triplet energy on phosphorescent molecules for highly-efficient organic blue-light- emitting devices', Appl. Phys. Lett., Vol. 83, p. 569, 2003   DOI   ScienceOn