Multimode high-sensitivity optical YVO₄:Ln³⁺ nanothermometers (Ln³⁺ = Eu³⁺, Dy³⁺, Sm³⁺) using charge transfer band features

Accurate thermal sensing with good spatial resolution is currently required in a variety of scientific and technological areas. Luminescence nanothermometry has shown competitive superiority in contactless temperature sensing, especially at the nanoscale. To broaden the use of such thermometers, development of a novel sensor type with high sensitivity and resolution is highly demanded. Herein, we report single-phase Ln3+-doped YVO4 nanophosphors synthesized using a modified Pechini method as multimode optical thermometers for wide-range temperature probing (299-466 K). The observed temperature-induced red shift of the charge transfer band was utilized to provide thermal sensing. Temperature sensing was based on the luminescence intensity ratio using emission intensities obtained upon charge transfer and direct lanthanide excitation, the spectral position of the charge transfer band and its bandwidth. The suggested probing strategies provided a high relative thermal sensitivity (up to 3.09% K-1) and a precise temperature resolution (up to 0.1 K). The obtained results can be useful for the design of novel contactless luminescence thermometers.