Influence of the nature of the dispersion medium on the optical properties of CdTe nanocrystals during sedimentation deposition

Abstract

The physicochemical properties of low-dimensional structures based on CdTe obtained are investigated by the method of colloidal synthesis. The analysis of the optical absorption spectra and the luminescence intensity of the CdTe colloidal NCs showed that the nature of the dispersion medium significantly affects their optical properties. The optical absorption spectra of the CdTe NK fractions obtained by dissolving the flocs in deionized water and in deionized water with the addition of NaOH have been shown to have the same character. However, the addition of NaOH results in a shift of the absorption maximum by 8-12 nm into the longwave region. This suggested that the addition of NaOH to the colloidal solution of NK CdTe during sedimentation deposition leads to the aggregation of cadmium telluride particles. The addition of NaOH results in the quenching of photoluminescence. It can be assumed that during the sedimentation deposition there is a leaching of THC to a critical concentration, therefore, due to insufficient stabilization of the surface of the NC CdTe, a rapid aggregation of particles occurs and a loss of sedimentation stability of the solution is observed, which causes the PL quenching. The analysis of the optical absorption and photoluminescence spectra of the fractions of the colloidal solution of NC CdTe obtained by using DMF as a dispersion medium during the sedimentation deposition leads to the conclusion that the nature of the dispersion medium significantly affects the optical properties of CdTe NC. The maxima of the OP spectra corresponding to the first exciton transition of all fractions are shifted to the longwave region and change their shape compared to the corresponding spectra for the aqueous fractions. In this case, the PL intensity of the first and second fractions of CdTe NC in DMF is approximately 100 ppm. exceeds the PL intensity of the aqueous fractions, which can be explained by the fact that DMF, unlike deionized water, does not wash out THC from the surface of the CdTe NC.