Afterglow-intensity-ratio-based temperature sensing using a persistent phosphor

Fluorescence intensity ratio (FIR)-based temperature-sensing techniques have received widespread attention in recent decades. However, the excitation light inevitably results in stray light and extra heat that will affect the accuracy of the thermometry. These drawbacks can be overcome via a non-real-time photo-excitation scheme using a persistent phosphor that is named here the afterglow intensity ratio (AIR) technique. Only several studies of AIR thermometry have been carried out where the Boltzmann equilibrium mechanism is mainly applied for manipulating the AIR. Here, we report highly sensitive AIR thermometry based on a thermal quenching (TQ) mechanism using the Y₃Al₂Ga₃O₁₂:Pr³⁺ persistent phosphor, which can generate an intense afterglow that originates from the 4f¹5d¹ → 4f² and ³P₀ → ³H₄ emissions of Pr³⁺ after ultraviolet charging. The AIR of the two emissions shows a strong temperature dependence in the range of 30-170 °C, giving a maximum relative sensitivity of up to 4.12% °C⁻¹ at 170 °C. The necessary high temporal stability of the AIR for accurate temperature measurement is proved. The application of the AIR technique is demonstrated via water-temperature measurement, where the error in the measurement is only 0.1 °C. Finally, we study and predicated some other persistent phosphors that showing application potential for AIR thermometry.