Fluorescence Characteristics of CdTe Quantum Dot Colloids below the Freezing Point

In this paper, water-soluble CdTe quantum dots (QDs) with different sizes from 3 to 3.9 nm are synthesized by the aqueous phase method using glutathione as the stabilizer, and their fluorescence properties below the freezing point are studied. The results show that the QD dispersion system still maintains the liquid state at −30 °C when the volume fraction of ethanol is 30%, and its fluorescence has a strong temperature dependence below the freezing point; as the temperature decreases from 0 to −30 °C, the fluorescence intensity increases about 62–82%, and the fluorescence emission peak also blue-shifts (5–10 nm). After cycles of heating (0 °C)–cooling (−30 °C), the fluorescence intensity can still be recovered, indicating a strong fluorescence reversibility. This work provides help for expanding the application of QDs in the fields of biomedicine.