Title: Investigation of pure green-colour emission from inorganic-organic hybrid LEDs based on colloidal CdSe/ZnS quantum dots

Authors: Nguyen Huu Tuan; Soonil Lee; Nguyen Nang Dinh

Addresses: Department of Physics and Division of Energy Systems Research, Laboratory of Nano Materials and Devices for Information Display, Ajou University, Suwon 443-749, South Korea ' Department of Physics and Division of Energy Systems Research, Laboratory of Nano Materials and Devices for Information Display, Ajou University, Suwon 443-749, South Korea ' Department of Nano Semiconductor Materials and Devices, University of Engineering and Technology, VNU Hanoi, Xuan Thuy Road, Cau Giay District, Hanoi, Vietnam

Abstract: We studied the operation characteristics of inorganic-organic hybrid light emitting devices (HLEDs) that have a green CdSe/ZnS quantum dot (QD) emitting layer (EML) and a 1,3,5-tris(N-phenylbenzimidazol-2-yl)-benzene (TPBi) hole blocking layer (HBL). A series of devices with a different thickness TPBi HBL all showed pure electroluminescence that is consistent with green photoluminescence of colloidal QDs without any colour contamination from organic layers. The best performance, which we attributed to more balanced charge carrier supply to a QD EML and efficient energy transfer from excitions in a TPBi layer to QDs, was observed from the device with a TPBi HBL of 20 nm thickness: the deep green emission with the luminous efficiency of 1.55 cd/A at standard video brightness (200 cd/m²) and the luminance as large as ~1800 cd/m².

Keywords: CdSe/ZnS; colloidal quantum dots; hybrid LEDs; hole blocking layer; electroluminescence; green photoluminescence; cadmium selenide; zinc sulphide; light emitting diodes; nanotechnology.

DOI: 10.1504/IJNT.2013.053144

International Journal of Nanotechnology, 2013 Vol.10 No.3/4, pp.304 - 312

Available online: 05 Apr 2013 *

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