Fluorescence quenching of CdSe quantum dots by tertiary amines and their surface binding effect

The effect of different amines on the fluorescence of quantum dots has been discussed in the literature but the mechanism involved is not fully understood. We have studied the interaction of core CdSe quantum dots of different sizes and core-shell CdSe quantum dots with tertiary amines, such as aliphatic amines (triethylamine) and bicyclic amines (DABCO and quinuclidine), using fluorescence techniques. Fluorescence quantum yield decreases with increasing concentration of the amine following a linear Stern-Volmer behaviour (Kq=80-330 M(-1)), but relatively small changes were observed in the fluorescence lifetimes. In order to get insights into the mechanism involved, small nanoparticles (2.1 nm) were synthesized and the interaction QD surface-amine was analysed by NMR and FTIR spectroscopy.