Scientific-Practical Materials Research Centre of the NAS of Belarus, Belarus

The efficiency of contactless upconversion luminescent intracellular temperature sensors based on yttrium orthovanadate and sodium tetrafluoroyttria nanocrystals doped with trivalent ytterbium and erbium rare earth ions was analyzed. The temperature sensitivity of parameters such as the luminescence band position, band width, and luminescence line intensity ratio were compared. The luminescence band position was found to have the highest temperature sensitivity. Methods for controlling the luminescence intensity and spectral composition can be based on optimizing nanoparticle size, controlling the concentration of donor and acceptor impurities, and using shells with a wider band gap. Electron-phonon interaction was shown to shift and broaden the luminescence line. The dependence of luminescence on nanocrystal size is due to surface effects and phonon-mediated processes in the emitting ions. It has been shown that lowering the high-frequency phonon threshold in nanoscale sensors and, as a result, reducing the Debye temperature, leads to greater temperature sensitivity of upconversion luminescence parameters