Efficient blue mechanoluminescence in Eu2+-Activated Sr5(PO4)3Cl for advanced anticounterfeiting with mildew-resistant behavior

Mechanoluminescent (ML) materials, exhibiting light emission upon external mechanical stimulation, offer considerable potentials in sensing, imaging, and anti-counterfeiting technologies. However, the scarcity of efficient blue ML materials and the requirement of pre-irradiation severely restrict their practical applications. In this work, Eu2+-activated Sr5(PO4)3Cl phosphors were synthesized under ambient conditions, and their luminescent properties were investigated when incorporated into a polydimethylsiloxane (PDMS) elastomer matrix. Notably, intense blue ML with strain-dependent intensity, non-pre-irradiation and self-recovery activities was achieved. By analyzing the interfacial triboelectricity, cathodoluminescence, thermoluminescence, and matrix effect, it was demonstrated that the ML of Sr5(PO4)3Cl:Eu2+ in PDMS should come from the electron bombardment processes induced by the interfacial triboelectricity, which was further verified by an ionic liquid incorporation strategy. Based on the unique ML properties of Sr5(PO4)3Cl:Eu2+/PDMS elastomer, advanced anti-counterfeiting devices with mildew-resistant behavior were developed. This research offers a fresh perspective on the development and design of ML materials, and presents attractive approaches for advancing the ML applications.