Luminescence nanothermometry via white light emission in Ho3+, Tm3+: Y2O3 colloidal nanocrystals

Cubic Ho3+ and Tm3+ doped Y2O3 colloidal nanotriangles with lateral length sizes ~43 nm, were synthesized via thermal decomposition methodology. These colloidal nanocrystals, upon high power excitation at 808 nm, generate white light. The crystalline structure, size and shape, and the surface of the colloidal nanocrystals, were investigated before and after being exposed to laser excitation. Factors that might affect the generation of white light, such as the power of excitation source, the stability of the emission with time, and the temperature at which the colloidal nanocrystals were exposed, are analyzed. The white light displayed temperature-dependence optical properties, allowing the application of these nanocrystals as luminescent nanothermometers over a wide range of temperatures, from room temperature to 473 K. The relative thermal sensitivity and the temperature resolution of these luminescent nanothermometers are 3.38% K-1 and 0.15 K, respectively, at 473 K, enabling to demonstrate a new highly sensitive mechanism for luminescence thermometry.