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 language | English |
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Pages (from-to) | 331-336 |
Number of pages | 6 |
Journal | Nano letters |
Volume | 12 |
Issue number | 1 |
DOIs | |
Publication status | Published - 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