Multimode -responsive luminescence of robust Sr2Ga2SiO7:Zn/Er/Pr for visualized/dynamic anticounterfeiting and temperature/stress sensing

Abstract

Various optical signals are popularly harnessed to realize anticounterfeiting, encryption, and photoluminescence (PL)-based sensing. However, most phosphors can only achieve single PL output under a fixed excitation, thus simultaneous attainment of multimodal PL behaviors remains an imperative pursuit. Herein, a highly integrated multimodal photon-, temperature-, and mechanically responsive Sr₂Ga₂SiO₇:Zn²⁺/Er³⁺/Pr³⁺(SGS:Zn/Er/Pr) is designed/synthesized via a facile solid-state reaction, endowing tunable down/up-converted (DC/UC) PL, mechanoluminescence (ML), and long-persistent PL (LPL) owing to the synergistic effects of self-activated and dopant-induced electronic transitions. serves as both an emitter and a trap center for the self-(L)PL located at ∼468 nm under λ_ex = 267 nm. These behaviors are further optimized by adjusting the content of and by forming a bridge () between trap levels upon Zn²⁺ incorporation. The excitation and Zn²⁺ content-dependent PL can be modified from blue to cyan via conflating dual self-PL from the ⁴T₁ → ⁴A₁ transition of Ga³⁺ at ∼402 nm and . The green DC/red UC PL from Er³⁺is observed under λ_ex = 357 and 980 nm, respectively. Nonequivalent substitution of Pr³⁺ at the Sr²⁺site and the incorporation of Zn²⁺ can adjust the charge transfer band energy level position and optimize the trap distribution, achieving long-term storage and highly repeatable/efficient LPL/ML generation. Based on abundant PL multimodes, the single-phased SGS:Zn/Er/Pr shows promising applications in sophisticated anticounterfeiting and latent fingerprint detection. Concurrently, owing to the coupled energy levels ²H_11/2/⁴S_3/2 of Er³⁺and the pressure-dependent ML of Pr³⁺, the SGS:Zn/Er/Pr is also suitably applied as a temperature/stress sensing agent.