Persistent- and Mechanoluminescence of Er³⁺-Doped NaYF₄ for Multipurpose Use

Advanced functional materials that possess both persistent luminescence (PersL) and mechanoluminescence (ML) have gained considerable attention during the past few years owing to their potential applications in many fields such as two-dimensional stress sensing, energy-saving lighting, and optical bioimaging. However, combined investigation of PersL and ML is still in its infancy. Here, the optical property of Er³⁺-doped NaYF₄, mainly focusing on the PersL and ML characteristic and their correlation, is studied in detail. It is shown that microscaled NaYF₄:Er³⁺ has advantages against nanoscaled counterpart in terms of PersL and ML, consistent with the photoluminescence results. By means of pre-charging and trap-emptying cycle and thermoluminescence test, it is confirmed that the PersL and ML of NaYF₄:Er³⁺ come from the same trapped charge carriers, and the ML belongs to the trap-controlled ML. Furthermore, the good repeatability is proven, and regulation of the PersL and ML of NaYF₄:Er³⁺ is realized. Finally, the potential of NaYF₄:Er³⁺ for dynamic anti-counterfeiting and dual-mode detection of X-ray radiation dose is demonstrated.