Mechanoluminescence from Visible to Second Near‐Infrared Region Based on Sr₃Sn₂O₇ Matrix

In recent years, mechanoluminescent (ML) materials have shown great potential in damage diagnosis, dynamic force sensing, and in vivo stress imaging. However, their development remains limited by the scarcity of suitable material systems and narrow spectral coverage. Here, a derived layered perovskite Sr 3 Sn 2 O 7 host with high defect tolerance, enabling broadband ML (from visible to the second near‐infrared window, 450–1600 nm) via lanthanide (Ln 3+ ) doping is reported. Owing to the exceptional defect tolerance of the host, multiple emission modes, including photoluminescence (PL), persistent luminescence (PersL), X‐ray excited luminescence (XEL), and ML are integrated into a single material system. This platform exhibits excellent force–luminescence linearity, cycling stability, and thermal adaptability. The ML intensity reaches up to 30 times that of PersL, offering a high signal‐to‐noise ratio for stress sensing. Furthermore, the multimodal luminescence properties enable demonstrations of practical applications in spatiotemporal encryption‐based anti‐counterfeiting, X‐ray sensing, and biomechanical stress detection. This work not only highlights the essential role of defect engineering in the development of ML materials but also provides a versatile platform for applications in smart sensing, human–machine interaction, and advanced anti‐counterfeiting technologies.