OPTICAL PROPERTIES OF CdS QUANTUM DOTS SYNTHESIZED AT DIFFERENT CONCENTRATIONS OF REAGENTS
The paper presents the results of the investigation of quantum dots of cadmium sulfide synthesized by sol-gel technology in a gelatin matrix. Samples were obtained with different contents of the initial reagents. The concentrations were varied from 2·10-4 atom % up to 1.0 atom % relative to the water contained in the reactor. The crystal lattice of the CdS quantum dots has a cubic structure. Using the methods of transmission electron spectroscopy, X-ray diffractometry and optical spectroscopy, the size of quantum dots have determined. The values of which varies from 1 nm to 3.5 nm. The synthesis conditions are determined for films of QDs CdS samples in the gelatin matrix which have a maximum luminescence intensity. The size of the corresponding QDs CdS is d = 2.1 ± 0.2 nm.
The luminescence band maxima shift to the long-wavelength region of the spectrum when the dimensions of the CdS quantum dots increase in accordance with the quantum-size effect.
The change in the diameter of quantum dots from 1 nm to 2.1 nm is accompanied by an increase in the luminescence intensity to a maximum value. The experimental average rate of increase in the luminescence intensity was comparisoned with the same average rate calculated on the assumption that the luminescence intensity of the sample is proportional to two parameters: the number of luminescence centers in QDs, which proportional to the volume of QD, and the amount of QD in the sample. It was found that the experimental average rate of increase in the luminescence intensity have exceeded the calculated.
The results of the experiment (TEM image and XRD pattern) were obtained using the equipment of the Center for Collective Use of Scientific Equipment of Voronezh State University
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