Photo-induced interaction of thioglycolic acid (TGA)-capped CdTe quantum dots with cyanine dyes

By Mostafa F. Abdelbar and Tarek A. Fayed and Talaat M. Meaz and El- Zeiny M. Ebeid
Published in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy NULL 2016

Abstract

The photo-induced interaction of three different sizes of thioglycolic acid (TGA)-capped CdTe quantum dots (CdTe QDs) with two monomethine cyanine dyes belonging to the thiazole orange (TO) family has been studied. Positively charged cyanines interact with \QDs\ surface which is negatively charged due to capping agent carboxylate ions. The energy transfer parameters including Stern-Volmer constant, Ksv, number of binding sites, n, quenching sphere radius, r, the critical energy transfer distance, R0, and energy transfer efficiencies, E have been calculated. The effect of structure and the number of aggregating molecules have been studied as a function of CdTe \QDs\ particle size. Combining organic and inorganic semiconductors leads to increase of the effective absorption cross section of the \QDs\ which can be utilized in novel nanoscale designs for light-emitting, photovoltaic and sensor applications. A synthesized triplet emission of the studied dyes was observed using CdTe \QDs\ as donors and this is expected to play a potential role in molecular oxygen sensitization and in photodynamic therapy (PDT) applications.

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