Dual-mode broadband NIR photon- and mechanoluminescence in high entropy oxide Ca2TbScGa2Ge2O12:Cr3+

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.