Proceedings of the Korean Vacuum Society Conference (한국진공학회:학술대회논문집)

The Korean Vacuum Society (한국진공학회)
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Inverted CdSe/ZnS Quantum Dots Light-Emitting Diode Using Low-Work Function Organic Material Polythylenimine Ethoylated

  • Kim, HongHee (Interface Control Research Center, Future Convergence Technology Research Division, Korea Institute of Science and Technology) ;
  • Son, DongIck (Soft Innovative Materials Research Center, Korea Institute of Science and Technology) ;
  • Jin, ChangKyu (Interface Control Research Center, Future Convergence Technology Research Division, Korea Institute of Science and Technology) ;
  • Hwang, DoKyung (Interface Control Research Center, Future Convergence Technology Research Division, Korea Institute of Science and Technology) ;
  • Yoo, Tae-Hee (Interface Control Research Center, Future Convergence Technology Research Division, Korea Institute of Science and Technology) ;
  • Park, CheolMin (Department of Materials Science and Engineering Yonsei University) ;
  • Choi, Won Kook (Interface Control Research Center, Future Convergence Technology Research Division, Korea Institute of Science and Technology)
  • Published : 2014.02.10
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Abstract

Over the past several years, colloidal core/shell type quantum dots lighting-emitting diodes (QDLEDs) have been extensively studied and developed for the future of optoelectronic applications. In the work, we fabricate an inverted CdSe/ZnS quantum dot (QD) based light-emitting diodes (QDLED). In order to reduce work function of indium tin oxide (ITO) electrode for inverted structure, a very thin (<10 nm) polyethylenimine ethoxylated (PEIE) is used as surface modifier[1] instead of conventional metal oxide electron injection layer. The PEIE layer substantially reduces the work function of ITO electrodes which is estimated to be 3.08 eV by ultraviolet photoemission spectroscopy (UPS). From transmission electron microscopy (TEM) study, CdSe/ZnS QDs are uniformly distributed and formed by a monolayer on PEIE layer. In this inverted QDLEDs, blend of poly (9,9-di-n-octyl-fluorene-alt-benzothiadiazolo) and poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] are used as hole transporting layer (HTL) to improve hole transporting property. At the operating voltage of 8 V, the QDLED device emitted spectrally orange color lights with high luminance up to 2450 cd/m2, and showed current efficacy of 0.6 cd/A, respectively.

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