Lanthanide-containing visible-light-excited thermosensitive luminescent films

Among the methods of temperature measurement, luminescent thermometry has recently become increasingly interesting due to a number of advantages over traditional thermometers such as high sensitivity and spatial resolution, no need for contact with the analyzed object, and the capability for remote monitoring of temperature fields in complex conditions. Despite the obvious advantages, the practical application such sensors are currently limited by the following problems: low photo- and thermal stability, the use of UV sources for their excitation and the difficulty of obtaining thin-film materials. In this work, we propose a simple approach to developing visible-light-excited temperature sensors based on films of an anisometric Eu(III) complex by performing their vitrification from the melt. Due to formation of J-aggregates, the spectra of such microscale films contain an intensive excitation band at ∼400 nm, which allows for activating their luminescence not only by UV light but also by inexpensive visible light sources with the absorption range wavelengths of 390-425 nm. The impact of temperature on the luminescence intensity and lifetime of the films excited by visible light was studied. The ranges of temperature measurement and sensitivities of the produced films were evaluated. The films demonstrated high temperature sensitivity of their luminescence equal to 18.97 μs/K. The produced materials can reversibly change their luminescent parameters in the temperature range of 298-353 K. The studied temperature-sensitive material can be excited by inexpensive sources of visible light. Such an approach is promising for enhancing the photostability of sensing elements and reducing the overall cost of temperature measurement devices.