Enhanced near-infrared mechanoluminescence through energy transfer between Tb3+-Cr3+ pairs in smart oxides

Near-infrared (NIR) mechanoluminescent materials are attracting significant attention due to their potential applications in biomedical imaging, food analysis, and night vision. In this study, Tb 3 Al 5 O 12 :Cr 3+ (TAG:Cr 3+ ) phosphors were successfully synthesized using a conventional high-temperature solid-state method. These materials demonstrated enhanced NIR luminescence through energy transfer (ET) between Tb 3+ and Cr 3+ . The structural and luminescent properties of the TAG:Cr 3+ phosphors were systematically investigated, revealing a strong spectral overlap between the emission of Tb 3+ and the excitation of Cr 3+ , which facilitates efficient ET. When embedded in polydimethylsiloxane (PDMS) composites, the phosphors exhibited notable mechanoluminescence (ML) properties, showing robust response and recoverability under repeated mechanical stimulation. Density functional theory (DFT) calculations further elucidated the luminescence mechanism at the atomic scale, highlighting charge transfer interactions between the TAG:Cr 3+ phosphors and the PDMS matrix. The analysis of ML intensity versus applied force using grayscale values enabled more accurate determination of their linear relationship. Furthermore, the prepared NIR pc-LEDs demonstrated strong performance in applications such as tissue imaging, food damage detection, and night vision. Meanwhile, the NIR-ML films showed promising potential for in vivo bio-stress imaging. These findings pave the way for the development of high-performance, multimodal NIR-emitting materials for diverse applications.