Efficient and low potential operative host/guest concentration graded bilayer polymer electrophosphorescence devices

Jung Kyu Kim, Dong Hyun Lee, Dong Hwan Wang, Sung M. Cho, Jun Young Lee, Jong Hyeok Park

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3 Citations (Scopus)


This study investigates enhanced electrophosphorescence and its mechanism in poly(N-vinyl carbazole) (PVK): N,N′-diphenyl-N,N′-bis(3- methylphenyl)-[1,1-biphenyl]-4,4′-diamine (TPD)/2-(4-biphenylyl)-5-(4- tert-butylphenyl)-1,3,4-oxadiazole (PBD): fac-tris(2-phenylpyridine)iridium [Ir(ppy) 3] concentration graded bilayer electroluminescence devices. The two layers are partially intermixed at the bilayer interface because the upper layer (composed of Ir(ppy) 3 and PBD) was spun cast from a solvent that slightly swells the bottom layer (composed of PVK and TPD). Moreover, PBD in the upper layer can act as an efficient electron transport layer as well as a hole blocking layer, resulting in greatly enhanced electronhole recombination. An indium tin oxide (ITO)/3,4- polyethylenedioxythiophenepolystyrenesulfonate (PEDOT)/[PVK:TPD/Ir(ppy) 3:PBD] bilayer/LiF/Al device showed dramatically decreased turn-on and driving voltages, enhanced luminescence efficiency, and narrower emission spectra compared to those of conventional ITO/PEDOT:PSS/[PVK:TPD:Ir(ppy) 3:PBD] blend/LiF/Al devices.

Original languageEnglish
Pages (from-to)870-874
Number of pages5
JournalJournal of Luminescence
Issue number3
Publication statusPublished - 2012 Mar

Bibliographical note

Funding Information:
This research was supported by Research Programs through the NRF grant funded by MEST (nos. 20100026281 , 20110023215 ). This work (Prof. J.H. Park) was also partially supported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, Republic of Korea .

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Atomic and Molecular Physics, and Optics
  • Chemistry(all)
  • Biochemistry
  • Condensed Matter Physics


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