Upconversion thermometry: a new tool to measure the thermal resistance of nanoparticles

The rapid evolution in luminescence thermometry in the last few years gradually shifted the research from the fabrication of more sensitive nanoarchitectures towards the use of the technique as a tool for thermal bioimaging and for the unveiling of properties of the thermometers themselves and of their local surroundings, for example to evaluate heat transport at unprecedented small scales. In this work, we demonstrated that KLu(WO 4 ) 2 :Ho 3+ ,Tm 3+ nanoparticles are able to combine controllable heat release and upconversion thermometry permitting to estimate its thermal resistance (in air), a key parameter to model the heat transfer at the nanoscale. We demonstrated that KLu(WO 4 ) 2 :Ho 3+ ,Tm 3+ nanoparticles are able to combine controllable heat release and upconversion thermometry permitting to estimate the thermal resistance of the nanoparticles in air, a key parameter to model the heat transfer at the nanoscale.