Super‐Encryption of Full‐Color Fluorescent Hologram in Carbon Dot Assemblies

Abstract The optical encryption strategy based on the combination of fluorescence and polarization holography has significant advantages in multi‐dimensional coding and visual security, and plays a crucial role in information protection. However, building a robust dual‐functional platform with full‐color fluorescence tunability and large storage capacity still remains a big challenge. Herein, fluorescent carbon dots (CDs) are assembled into gridded titania (TiO ₂ ) scaffolds for ultra‐high‐level holographic encryption. The construction of the fluorescence‐holography encryption layer utilizes both the polarized spectral hole‐burning of CDs/TiO ₂ based on directional interface charge transfer and the fluorescence emission characteristics of CDs monomers. Chromaticity information is assigned to Quick Response (QR) code patterns under UV excitation. Then, micrometric computer‐generated holograms (CGHs) are written into the CDs/TiO ₂ region, which exhibits significant polarization dependence. The decryption of true information requires the super verification with color, coordinate, polarization, wavelength, and logical judgment. The platform demonstrates excellent optical and thermal stability, maintaining over 97% fluorescence intensity under prolonged UV irradiation, and persistent holographic reconstruction efficiency at 433 K for at least 30 h. This work integrates color display, fluorescence switch, and polarization holography, providing a promising path for high‐security optical anti‐counterfeiting and information encryption.