Irreversible Ca₂B₂O₅-Based Multicolor Mechanoluminescence for Security Labels

As the Internet of Things (IoT) continues its pervasive influence and digital technologies increasingly weave into the fabric of daily lives, the imperative for robust security measures becomes paramount to mitigate the escalating risks to the digital landscape. Traditional anti-counterfeiting technologies, while capable to some extent, are constrained by factors such as material toxicity, low-security efficacy, and intricate fabrication process. Mechanoluminescent materials have shown great potential in the areas of anti-counterfeiting and security. Here, a multicolor mechanoluminescent (ML) material (lanthanide doped Ca2B2O5) synthesized by solid-phase reaction is reported for the first time at a relatively lower temperature of 750 degrees C. The ML devices are obtained by embedding ML materials into polydimethylsiloxane elastomer, allowing for stress visualization with colors ranging from blue and green to orange and red. Through elaborate co-doping, successive and accurate stress visualizations are realized. Finally, security labels based on the lanthanide ions doped Ca(2)B(2)O(5 )are prepared and also demonstrated to safeguard valuable packages. This work provides a novel multicolor ML material and pioneers its use in security labels, offering a universal solution for multicolor display, information security, dynamic anti-counterfeiting, and other potential applications within the realm of IoT.