Temperature- and Emission Wavelength-Dependent Time Responses of Strontium Aluminates

In this paper, we study the temperature- and emission wavelength-dependent time responses of previously reported precursor-driven Eu²⁺- and Dy³⁺-doped strontium-aluminate phosphors to create unique luminescent anti-counterfeiting tags suitable for detection with smartphones. A smartphone was used to detect the red–green–blue (RGB) components of the rise and decay time responses of the samples in a temperature range from 0 °C to 100 °C. The RGB color-dependent detection revealed a finer excitation/relaxation kinetics structure of the individual samples, which becomes evident in the decay responses. The results suggest another possibility for multilevel encoding and temperature sensor applications, and provides a foundation for developing a more accurate theoretical model of the energy transitions in phosphorescent materials.