Substrate and Luminescence properties of CdSe/CdS/ZnS Quantum Dots

Abstract

The photoluminescence of CdSe/CdS/ZnS quantum dots (QDs) deposited at solid surfaces (ITO) is considered for three types of organization:  QDs directly adsorbed on solid surfaces, separated from the solid surface by a nanoscale liquid crystal (8CB) film with different thickness.
The luminescence spectra were obtained at different film irradiation times. Irradiation was performed by a laser with a wavelength of 473 nm in a pulsed mode and an optical power of 10 mW. The laser spot diameter was about 300 nm, and the exposure time was 1 s. It is noticeable that with an increase in the duration of exposure to laser radiation on the film, the value of the maximum luminescence intensity decreases. Figure 1, shows a typical series of spectra (54 s duration) for a CdSe/CdSe/ZnS QD film. At the beginning, the emission peak falls at ~528.9 nm, and then shifts slightly to the blue region. After 54 seconds of exposure, this shift is about 6.7, 5.6 and 4.3 nm, and its intensity decreases by 85.9, 62.7 and 50% for the systems (QDs), (QDs + 8CB monolayer) and (QDs+ 8CB three-layer film), respectively
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It was shown that the luminescence properties of thin QD films on a ITO surface can be tuned by adding a nanosized 8CB film (about 6 nm thick) between the QD layer and the substrate. It can be seen that the luminescence peak shifts hypsochromically to the blue region during irradiation. It was found that the luminescence intensity decreased by 35%.

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AL-ALwani Ammar Jaber
Saratov State University
Russia

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