Investigation of the optical properties of quantum dots depending on the nature and number of additional semiconductor layers

The present study aims to investigate the properties of quantum dots (QDs) depending on the nature and number of additional semiconductor layers. The analysis of spectral data showed that when CdTe QDs are coated with a ZnS shell, a bathochromic shift of the exciton peak and maximum of fluorescence is observed due to the restriction of charge carriers in the nucleus. However, the build-up of the additional shell leads to a decrease in the quantum yield,
which may be due to the difference in the parameters of the crystal lattices to CdS and ZnS and the occurrence of defects in the crystal structure. In contrast, CdTe QDs coated with a CdS shell increased the quantum yield and shifted the peak of fluorescence to a longer wavelength region.