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

Jun Zhang,Jian-Qing Zhou,Kun Zhang,Su-Qing Zhao,Yan-Fei Cai

doi:10.1186/1556-276x-7-405

Jun Zhang, Jian-Qing Zhou + Show 3 more

Open Access

https://doi.org/10.1186/1556-276x-7-405

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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.

Highlights

Sol–gel-derived materials have received particular interest as chemical receptor matrices because of their optical transparency, mechanical stability, chemical resistance and flexibility in sensor morphological configurations
TEM images of undoped ZnO quantum dots (QDs) and ZnO QDs doped with 2%, 5%, 10% and 20% Cd are shown in Figure 1A,B, C,D,E, respectively
The images reveal that the particle sizes of the Cd-doped ZnO QDs are significantly less than those of undoped ZnO QDs

Summary

Introduction

Sol–gel-derived materials have received particular interest as chemical receptor matrices because of their optical transparency, mechanical stability, chemical resistance and flexibility in sensor morphological configurations. The materials have a wide spectrum of advantages: they may be set up at room temperature, they are not degraded electrochemically or by light, they are open to a wide variety of chemical modifications, they can be obtained in a variety of forms (monoliths, thin films, fibres or powders), and they are able to respond rapidly The combination of these factors makes these materials desirable for use in the pharmaceutical, food and chemical industries [1]. Particles aggregate during the preparation of ZnO QDs because of their large specific surface area and high surface activity This aggregation can create an irregular surface, which causes many disadvantages in the final products. The formation of Zn1-xCdxO alloys from ZnO and CdO can cause the band gap of

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