High Defect Tolerance Breaking the Design Limitation of Full‐Spectrum Multimodal Luminescence Materials

Abstract With the development of optical anti‐counterfeiting and the increasing demand for high‐level information encryption, multimodal luminescence (MML) materials attract much attention. However, the discovery of these multifunctional materials is very accidental, and the versatile host suitable for developing such materials remains unclear. Here, a grossite‐type fast ionic conductor CaGa 4 O 7 , characterized by layered and tunnel structure with excellent defect tolerance, is found to meet the needs of various luminescent processes. Almost all luminescent modes, including down/up‐conversion luminescence (DCL/UCL), long persistent luminescence (LPL), mechanoluminescence (ML), and X‐ray excited optical luminescence (XEOL), are realized in this single host. Full‐spectrum (from violet to near‐infrared) photoluminescence and ML as well as multicolor XEOL are achieved by simply changing the doped luminescent center. A series of anti‐counterfeiting devices, including the quasi‐dynamic display of famous paintings, digital information encryption, and multi‐color handwritten signatures, are designed to show the encryption of information in temporal and spatial dimensions. This study clarifies the importance of defect tolerance of the host for the development of MML materials, and provides a unique insight into the cross‐field applications of special functional materials, which is a new strategy to accelerate the development of novel MML materials.