Dual-mode broadband NIR photon- and mechanoluminescence in high entropy oxide Ca 2 TbScGa 2 Ge 2 O 12 :Cr 3+

In this study, a novel, to the best of our knowledge, Cr³⁺-doped garnet fluorescent material (Ca₂TbScGa₂Ge₂O₁₂:Cr³⁺, CTSGGO:Cr³⁺) in high-entropy oxides has been successfully synthesized by a high-temperature solid-phase method and systematically investigated in terms of its photoluminescence (PL) and mechanoluminescence (ML) properties. The material shows broadband near-infrared emission in the 700-900 nm range when excited by 460 nm blue light, with a half-peak width of 116 nm. Additionally, it achieves NIR-visible synergistic emission in both PL and ML modes through efficient energy transfer from Tb³⁺ to Cr³⁺ (with a transfer efficiency of 75%). When encapsulated in PDMS, the material exhibits dual ML responses: 450-650 nm (Tb³⁺) and 650-900 nm (Cr³⁺) under mechanical stress. It was integrated with commercial blue LED chips and PDMS for practical applications in night vision imaging, tissue penetration visualization, and multiple-mode optical anti-counterfeiting. This work offers new insights for designing broadband NIR-emitting materials and developing photoelectronic and force-responsive devices.