Electroluminescence of different colors from polycation/CdTe nanocrystal self-assembled films

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Gao Mingyuan
  • Constanze Lesser
  • Stefan Kirstein
  • Elmuth Möhwald
  • Horst Weller

Detail(s)

Original languageEnglish
Pages (from-to)2297-2302
Journal / PublicationJournal of Applied Physics
Volume87
Issue number5
Online published17 Feb 2000
Publication statusPublished - Mar 2000
Externally publishedYes

Abstract

Water soluble thiol capped CdTe nanocrystals are assembled into ultrathin films in combination with poly(diallyldimethylammonium chloride) (PDDA) by the self-assembly method of layer-by-layer adsorption of oppositely charged polyelectrolytes. Electroluminescent devices, which produce different color emissions, are fabricated by sandwiching CdTe/PDDA films between indium-tin-oxide (ITO) and aluminum electrodes using CdTe nanocrystals of different sizes. It is shown that the electroluminescence (EL) spectra of the CdTe/polymer films are nearly identical to the photoluminescence spectra of the corresponding CdTe nanocrystals in aqueous solutions. The devices produce room-light visible light output with an external quantum efficiency up to 0.1%. Light emission is observed at current densities of 10 mA/cm2 and at low onset voltages of 2.5-3.5 V, which depends on the thickness of the film indicating field-dependent current injection. A variation of the EL efficiency with the size of the CdTe particles is observed and explained by the size dependent shift of the CdTe energy levels with respect to the work function of the electron injecting Al electrode. This is confirmed by the behavior of two-layer devices prepared from two differently sized CdTe particles being spatially separated, i.e., one size CdTe near ITO and the other size CdTe near Al by using the self-assembly method. © 2000 American Institute of Physics.

Citation Format(s)

Electroluminescence of different colors from polycation/CdTe nanocrystal self-assembled films. / Mingyuan, Gao; Lesser, Constanze; Kirstein, Stefan et al.
In: Journal of Applied Physics, Vol. 87, No. 5, 03.2000, p. 2297-2302.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review