Highly Efficient Cadmium-Free Quantum Dot Light-Emitting Diodes Enabled by the Direct Formation of Excitons within InP@ZnSeS Quantum Dots

Title
Highly Efficient Cadmium-Free Quantum Dot Light-Emitting Diodes Enabled by the Direct Formation of Excitons within InP@ZnSeS Quantum Dots
Authors
Jaehoon LimMyungjin Park배완기Donggu LeeSeonghoon LeeChanghee LeeKookheon Char
Keywords
InP quantum dots; core@shell heterostructure; electroluminescence devices; conjugated polyelectrolyte
Issue Date
2013-10
Publisher
ACS Nano
Citation
VOL 7, NO 10, 9019-9026
Abstract
We demonstrate bright, efficient, and environmentally benign InP quantum dot (QD)-based light-emitting diodes (QLEDs) through the direct charge carrier injection into QDs and the efficient radiative exciton recombination within QDs. The direct exciton formation within QDs is facilitated by an adoption of a solution-processed, thin conjugated polyelectrolyte layer, which reduces the electron injection barrier between cathode and QDs via vacuum level shift and promotes the charge carrier balance within QDs. The efficient radiative recombination of these excitons is enabled in structurally engineered InP@ZnSeS heterostructured QDs, in which excitons in the InP domain are effectively passivated by thick ZnSeS composition-gradient shells. The resulting QLEDs record 3.46% of external quantum efficiency and 3900 cd m–2 of maximum brightness, which represent 10-fold increase in device efficiency and 5-fold increase in brightness compared with previous reports. We believe that such a comprehensive scheme in designing device architecture and the structural formulation of QDs provides a reasonable guideline for practical realization of environmentally benign, high-performance QLEDs in the future.
URI
http://pubs.kist.re.kr/handle/201004/46083
ISSN
19360851
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KIST Publication > Article
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