Metal–Organic Framework-Activated Full-Color Room-Temperature Phosphorescent Carbon Dots with a Wide Range of Tunable Lifetimes for 4D Coding Applications

Carbon dots (CDs) that simultaneously exhibit full-color and wide-range lifetime-tunable room-temperature phosphorescence (RTP) are of particular interest for potential applications in encryption and information security. However, achieving such CDs remains a great challenge thus far. This work reports on the development of a straightforward host–guest approach, where a metal–organic framework (MOF) host acts as an RTP activator of fluorescent CDs, with the RTP color dependent on the fluorescent component. The developed CDs@MOF composites exhibited RTP with a tunable emission wavelength from blue (478 nm) to red (631 nm), while the lifetime was tunable from 85.67 to 1064.21 ms. As far as is known, this is the report of CD-based RTP materials with simultaneous full-color and wide-range lifetime-tunable properties for the first time. In comparison to conventional 3D coding applications of CDs, the wide-range lifetime-tunable property allows for the creation of an additional dimension in encryption. Thus, the developed RTP CDs@MOF composites have potential as writable security inks for advanced 4D coding applications. This study paves a path for development of RTP CD-based nanomaterials with multiple controllable factors to meet the requirements of advanced applications.