Multi-color mechano-luminescence of LaGaO3:Sm3+,Tb3+ via trap sharing for anti-counterfeiting and encryption

Mechano-luminescence (ML) has been found diverse applications such as stress sensing, 3-D signature, energy harvesting, and anti-counterfeiting, due to the unique properties of the corresponding ML phosphors performing in-situ and real-time response to mechanical stimulus. Trap-controlled ML materials realize reproducible, quantitative mechano-optical conversion resulting from the released carriers for the trap-mediated charge storage and release. Herein, modulating traps matters the controllable ML behavior for their promising applications. In this work, a deep trap distributed ranging from 0.9 to 1.3 eV is realized consecutively for the introduction of Sm3+ ions into LaGaO3 matrix, which contributes to the red emission at 600 nm under mechanical stimuli. Moreover, tunable ML emission modulated from 600 to 545 nm is successfully achieved for the codopant of Tb3+ ions. It is unambiguously indicated that the released carriers from the trap sharing rather than an additional constructed trap contribute to the modulated ML color. Accordingly, multi-mode anti-counterfeiting and encryption are achieved with the as-explored Sm3+, Tb3+ co-activated ML phosphor.