Quantum-dots based materials for temperature sensing: effect of cyclic heating-cooling on fluorescence

Using the temperature dependence of the fluorescence of quantum dots (QDs) in the sensing of temperature is a promising field. In this work, we systematically study the effect of cyclic heating and cooling on the fluorescence of CdSe/ZnS QD and PMMA-QD composite in air. The experimental results show that increasing the temperature causes red-shift of the PL (photoluminescence) emission peak and the decrease of the PL intensity, and decreasing the temperature causes blue-shift of the PL emission peak and the increase of the PL intensity for all the QDs presented in both media. There exists a critical temperature, above which the heating completely damages the surface structures of the QDs and leads to the loss of the luminescence characteristics of the QDs. Placing CdSe/ZnS QDs in PMMA causes blue-shift of the PL emission peak, which likely is due to the shift of the ground state energy of the QDs. The heating-cooling cycle with high peak temperature up to 310 °C does not change the crystal structure of the ZnS in the CdSe/ZnS QDs.