The effect of ionic strength on spectral properties of quantum dots and aluminum phthalocyanine complexes

Abstract

The effect of ionic strength on spectral properties of negatively charged semiconductor (CdSe/ZnS) nanocrystals (quantum dots, QDs) and polycationic aluminum phthalocyanines (PCs) is considered. A QD/PC complex, formed via self-assembly, remains stable throughout a wide range of ionic strength values of a solution and [PC]/[QD] concentration ratio. The efficiency of nonradiative energy transfer from QDs to PCs rises with an increase in the ionic strength of solution. The fluorescence amplification factor of PC reduces with an increase in number of PC molecules in a complex with a quantum dot, reaching negative values at high [PC]/[QD] ratios. This is probably due to the decrease in the effect of energy migration on the total PC fluorescence upon its own significant absorption ability of a large number of acceptors. These effects are of interest to develop selection principles of components for hybrid complexes stabilized with electrostatic interaction.