Persistent phosphors are typically impurity doped luminescent materials that feature an energy storage step between the excitation (e.g. by exposure to daylight or UV) and the emission of light. This energy storage, which can last from seconds to days, is rooted in charge carriers being trapped at particular defects in the material. Thermal energy is then required to release the charge carriers, after which recombination and light emission occurs. In this seminar, I will highlight the state-of-the-art in the field, by showing the unique characteristics of current applications (like in safety signage or bioimaging) and the remaining challenges. The physico-chemical mechanisms of the trapping and detrapping processes are discussed, along with the key analytical and spectroscopic techniques applied to those materials.
In the second part, starting from those recent insights, persistent phosphors are turned into a versatile sensing platform for mechanical pressure, ultrasound, temperature, or optical and X-ray dosimetry. For each application, the relevant mechanisms are highlighted, as well as the remaining hurdles.
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