Universität zu Köln

Amini, Pegah, Dolatyari, Mahboubeh, Rostami, Ali, Rostami, Ghasem, Mathur, Sanjay and Torabi, Pouneh (2015). High-Performance Solution Processed Inorganic Quantum-Dot LEDs. IEEE Trans. Nanotechnol., 14 (5). S. 911 - 918. PISCATAWAY: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. ISSN 1941-0085

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Abstract

In this research paper, fabrication of novel CdSe\ZnS QD-LEDs with solution processing method is presented, and the impact of trap energy levels in the electron and hole transport levels on these QD-LEDs brightness is investigated. Two types of QD-LEDs are fabricated with ITO as the transparent anode electrode, NiO nanoparticles as the hole transport layer (HTL), CdSe\ZnS QDs as the luminescent layer, ZnO:Ga as the electron transport layer (ETL), and Al as the cathode electrode. The NiO nanoparticles are synthesized by the sol-gel or alternatively the electrochemical method. Formation of different trap levels is observed in the crystal structures of the NiO nanoparticles synthesized by each of these methods. Considering the electrochemically prepared NiO nanoparticles, it is found that the density of trap levels is higher in the crystal structure of the NiO nanoparticles synthesized by sol-gel method, and the device fabricated by the latter material shows higher performance. Calculation of the electronic structure of ZnO:Ga by DFT methods (GGA-PBE) indicates that doping of Ga in the structure of crystalline ZnO creates new energy levels in conduction band and intermediate bands at the bandgap of ZnO host. It facilitates electron injection from Al cathode to the ZnO:Ga ETL layer and from this layer to the QD-luminescent layer. The fabricated devices show turn-on lower voltages than 5 V in which a peak brightness of 500 and 340 cd.m(-2) is measured for the LEDs fabricated with sol-gel and electrochemically synthesized NiO nanoparticles, respectively.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Amini, Pegah UNSPECIFIED UNSPECIFIED UNSPECIFIED Dolatyari, Mahboubeh UNSPECIFIED UNSPECIFIED UNSPECIFIED Rostami, Ali UNSPECIFIED UNSPECIFIED UNSPECIFIED Rostami, Ghasem UNSPECIFIED UNSPECIFIED UNSPECIFIED Mathur, Sanjay UNSPECIFIED UNSPECIFIED UNSPECIFIED Torabi, Pouneh UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-393621
DOI:	10.1109/TNANO.2015.2461025
Journal or Publication Title:	IEEE Trans. Nanotechnol.
Volume:	14
Number:	5
Page Range:	S. 911 - 918
Date:	2015
Publisher:	IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Place of Publication:	PISCATAWAY
ISSN:	1941-0085
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Inorganic Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language LIGHT-EMITTING-DIODES; CHARGE-TRANSPORT; FILMS; ZNO Multiple languages Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/39362