Over 40 cd/A Efficient Green Quantum Dot Electroluminescent Device Comprising Uniquely Large-Sized Quantum Dots
- Authors
- Lee, Ki-Heon; Lee, Jeong-Hoon; Kang, Hee-Don; Park, Byoungnam; Kwon, Yongwoo; Ko, Heejoo; Lee, Changho; Lee, Jonghyuk; Yang, Heesun
- Issue Date
- May-2014
- Publisher
- AMER CHEMICAL SOC
- Keywords
- quantum dots; electroluminescence; current efficiency
- Citation
- ACS NANO, v.8, no.5, pp.4893 - 4901
- Journal Title
- ACS NANO
- Volume
- 8
- Number
- 5
- Start Page
- 4893
- End Page
- 4901
- URI
- https://scholarworks.bwise.kr/hongik/handle/2020.sw.hongik/16702
- DOI
- 10.1021/nn500852g
- ISSN
- 1936-0851
- Abstract
- Green CdSe@ZnS quantum dots (QDs) of 9.5 nm size with a composition gradient shell are first prepared by a single-step synthetic approach, and then 12.7 nm CdSe@ZnS/ZnS QDs, the largest among ZnS-shelled visible-emitting QDs available to date, are obtained through the overcoating of an additional 1.6 nm thick ZnS shell. Two QDs of CdSe@ZnS and CdSe@ZnS/ZnS are incorporated into the solution-processed hybrid QD-based light-emitting diode (QLED) structure, where the QD emissive layer (EMI) is sandwiched by poly (9-vinlycarbazole) and ZnO nanoparticles as hole and electron-transport layers, respectively. We find that the presence of an additional ZnS shell makes a profound impact on device performances such as luminance and efficiencies. Compared to CdSe@ZnS QD-based devices the efficiencies of CdSe@ZnS/ZnS QD-based devices are overwhelmingly higher, specifically showing unprecedented values of peak current efficiency of 46.4 cd/A and external quantum efficiency of 12.6%. Such excellent results are likely attributable to a unique structure in CdSe@ZnS/ZnS QDs with a relatively thick ZnS outer shell as well as a well-positioned intermediate alloyed shell, enabling the effective suppression of nonradiative energy transfer between closely packed EMI QDs and Auger recombination at charged QDs.
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Collections - Graduate School > Materials Science and Engineering > 1. Journal Articles
- College of Engineering > Materials Science and Engineering Major > 1. Journal Articles
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