'Giant' CdSe/CdS core/shell nanocrystal quantum dots as efficient electroluminescent materials: Strong influence of shell thickness on light-emitting diode performance

Bhola N. Pal, Yagnaseni Ghosh, Sergio Brovelli, Rawiwan Laocharoensuk, Victor I. Klimov, Jennifer A. Hollingsworth, Han Htoon

Research output: Contribution to journalArticle

268 Citations (Scopus)

Abstract

We use a simple device architecture based on a poly(3,4- ethylendioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-coated indium tin oxide anode and a LiF/Al cathode to assess the effects of shell thickness on the properties of light-emitting diodes (LEDs) comprising CdSe/CdS core/shell nanocrystal quantum dots (NQDs) as the emitting layer. Specifically, we are interested in determining whether LEDs based on thick-shell nanocrystals, so-called "giant" NQDs, afford enhanced performance compared to their counterparts incorporating thin-shell systems. We observe significant improvements in device performance as a function of increasing shell thickness. While the turn-on voltage remains approximately constant for all shell thicknesses (from 4 to 16 CdS monolayers), external quantum efficiency and maximum luminance are found to be about one order of magnitude higher for thicker shell nanocrystals (≥13 CdS monolayers) compared to thinner shell structures (<9 CdS monolayers). The thickest-shell nanocrystals (16 monolayers of CdS) afforded an external quantum efficiency and luminance of 0.17% and 2000 Cd/m 2, respectively, with a remarkably low turn-on voltage of ∼3.0 V.

Original languageEnglish
Pages (from-to)331-336
Number of pages6
JournalNano letters
Volume12
Issue number1
DOIs
Publication statusPublished - Jan 11 2012

Keywords

  • Auger recombination
  • CdSe/CdS
  • Giant nanocrystal quantum dot
  • QD-LED
  • core/shell
  • energy transfer

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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