To prepare the material, cadmium selenide/zinc sulphide (CdSe/ZnS) quantum dots are loaded into a high-temperature resistant SiO2 dielectric matrix. The CdSe/ZnS:SiO2 nanocomposite was solution fabricated to yield thermally stable thin films. The room-temperature optical absorption is measured and the temperature dependence of the photoluminescent emission is investigated from 295 to 525 K. The emission peak wavelength Stokes shifts and the full width at half maximum increases with temperature.

As shown in the figure, the quantum dot bandgap is 2.04 eV. Atomic force microscopy (AFM) of the thin film reveals a cluster distribution with a 3.6 nm average particle size. The temperature-dependent spectral shift of the photoluminescence under thermal cycle enables self-referenced intensity-based temperature measurements with 0.11 nm/oC sensitivity.

Multi-sensing applications

The next steps include optimization of the CdSe/ZnS:SiO2 material system and characterization of the high-temperature response via optical spectroscopy. The CdSe/ZnS:SiO2 nanocomposite can be applied in combination with other luminescent indicators for multi-sensing applications using the same immobilization chemistry. This research demonstrates the potential for new possibilities in quantum dot-based optoelectronic devices such as luminescence-based thermal sensors.

The researchers presented their results in the journal Nanotechnology.