Importance of evaluating the excitation intensity dependence of the temperature-dependent luminescence: Impact on optical thermometry and anti-thermal quenching performance

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Afterglow materials exhibit distinct temperature-dependent luminescence compared to general optical materials due to the presence of extra unique energy transfer paths from traps to luminescent centers. These paths include: 1) energy transfer through the conduction band (CB), and 2) energy transfer via quantum tunneling channels to various energy levels. These have a notable impact on both the overall intensity and the relative intensity of emission at different temperatures, which is often unintentionally overlooked. To investigate the influence of these additional paths on temperature-dependent luminescence, we employed a simple yet effective method of varying the excitation light intensity in Y2CaSnGa4O12:Pr3+, an afterglow material. And the influences on optical thermometer and anti-thermal quenching performance were illustrated comprehensively. We ultimately arrived at some interesting and widespread conclusions: 1) The performance of fluorescence intensity ratio (FIR) thermometry, which relies on excitation intensity, can be stabilized by avoiding the presence of charging traps. The high sensitivity of the afterglow intensity ratio (AIR)-based thermometry, which does not require an external light source, may be closely associated with the quantum tunneling process. 2) The performance of trap-assisted anti-thermal quenching is excitation intensity-dependent. We elucidated the specific contribution of traps that had previously been unaccounted for in earlier reports.