Emission spectral change of CdSe/ZnS quantum dots caused by the dilution with organic solvents

Abstract The emission spectra of CdSe/ZnS core-shell type quantum dots were observed after the dilution of their toluene solution with organic solvents (acetone, diethyl ether, n-hexane, toluene, methanol, and ethanol). In addition to the well-known solvent dependence of the emission efficiency and peak wavelength, it was found that they change over several hours after the dilution, depending on the solvent and the number density of the quantum dot. Based on the solubility of the capping organic ligand to each solvent, the observed time variations were explained in terms of the elution of capping molecules from the dot surface and the resulting change of the number of charge traps.