Open Access Nano Express

A study of photoluminescence properties and performance improvement of Cd-doped ZnO quantum dots prepared by the sol–gel method

Jun Zhang1, Su-Qing Zhao1*, Kun Zhang1, Jian-Qing Zhou1 and Yan-Fei Cai2*

Author affiliations

1 Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, People’s Republic of China

2 College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, People’s Republic of China

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Citation and License

Nanoscale Research Letters 2012, 7:405  doi:10.1186/1556-276X-7-405

Published: 18 July 2012

Abstract

In the present work, ZnO quantum dots (QDs) have been prepared by the sol–gel method, and the performance of the QDs has been improved. The effect of Cd concentration on the structural and luminescent properties of the QDs, as well as the effect of the mass ratio of trioctylphosphine oxide (TOPO)/octadecylamine (ODA), has been investigated. The ZnO and Cd-doped ZnO QDs have hexagonal wurtzite structures and are 3 to 6 nm in diameter. When the Cd content was increased, the QD particle size was reduced; this effect was confirmed in the corresponding ultraviolet–visible spectra. The fluorescence intensity was simultaneously enhanced significantly. Both the UV and fluorescence spectra were blue-shifted. The luminous intensity was further enhanced when the QDs were modified with TOPO/ODA. Fourier transform infrared and X-ray diffraction techniques proved that the polymer successfully coated the surfaces of the QDs. A TOPO/ODA mass ratio of 1:2 was determined to result in the best optical performance among the different ratios examined. The results showed that the described synthetic method is appropriate for the preparation of doped QDs with high-fluorescence quantum efficiency.

Keywords:
Cd-doped ZnO; Quantum dots; Sol–gel method; Photoluminescence properties