Effect of temperature on the preparation of CdS quantum dots using poly(amide amine) dendrimer templates

In order to study the effect of temperature on the preparation of CdS quantum dots (QDs) using poly(amide amine) (PAMAM) dendrimer templates, well-dispersed CdS QDs were synthesized with PAMAM dendrimers of generation 4.5 (G4.5, 64 terminal ester groups),in the temperature range from -10 to 30 degrees C. The morphology and the size of CdS QDs Were measured using TEM. The optical properties were characterized by UV-Vis spectra and photoluminescence (PL) spectra. The results show that the size of CdS QDs increased from 1.8 to 3.4 nm when the synthesis temperature was raised from -10 to 30 degrees C, and the size-distribution of QDs prepared at 10 degrees C was the narrowest; the absorption and, the PL spectra were red-shifted, while the PL intensity of CdS QDs prepared at 10 degrees C was the highest. These results suggest that the preparation temperature determines the de-coordination rate between the functional groups of PAMAM dendrimers and Cd2+, the rate of nucleation and growth of CdS QDs, the size and size-distribution of QDs, and the PL color and PL efficiency finally.