Multicolor luminescence from CaZnOS: Bi3+, Eu3+ for stress sensing and multimode anti-counterfeiting

The unique luminescent properties of mechanoluminescence (ML) have demonstrated immense potential for applications in fields such as mechanical sensing, anti-counterfeiting, and display imaging. In this work, a series of multicolor luminescent Ca0.95-xZnOS: 0.05Bi3+, xEu3+ (x = 0–0.04) were synthesized through the high-temperature solid-state reaction method. An energy transfer (ET) process from Bi3+ to Eu3+ was observed when Eu3+ was introduced. The introduction of Eu3+ led to an observed energy transfer process from Bi3+ to Eu3+. The photoluminescence (PL) color shifted from blue-green to red, and the afterglow (AG) shifted from blue to red as the concentration of Eu3+ increased. Furthermore, CaZnOS: Bi3+, Eu3+ exhibits red ML with the highest intensity of 3% Eu3+ concentration, which is 14% higher than CaZnOS: 0.05Bi3+. The ML intensity exhibits a linear correlation with the stress level and can be applied to stress sensing. Therefore, a light-emitting device composed of CaZnOS: Bi3+, Eu3+ and PDMS possesses three light-emitting modes: PL, AG, and ML, which is suitable for optical anti-counterfeiting.