Tailoring Full-Spectrum Solvatofluorochromic Carbon Dots: Deciphering Tunable Multicolor Emission Mechanisms toward Advanced Photonic Cryptography

The growing demand for high-security optical encryption and anticounterfeiting technologies necessitates the development of full-spectrum multimodal luminescence materials and strategies. However, integrating full-color emission and multilevel response modes within a single system remains challenging. Herein, a facile one-pot solvothermal strategy is developed to tailor two distinct carbon dots (CDs), dispersed CDs (d-CDs) and aggregated CDs (a-CDs), exhibiting full-spectrum multimodal photoluminescence. Systematic investigations reveal that the multicolor emission originates from intrinsic, deep defective, and surface states in both d-CDs and a-CDs, while a-CDs uniquely exhibit an additional molecular state via intramolecular charge transfer. Remarkably, the photoluminescence behavior can be dynamically modulated by solvent polarity and hydrogen bonding, enabling on-demand full-spectrum photoluminescence responses. With the leverage of these exceptional full-spectrum solvatofluorochromic properties, advanced encryption platforms with high-level security are demonstrated. This work not only deciphers the multicolor emission origins and solvatofluorochromic mechanisms of CDs but also offers new perspectives for designing intelligent materials for optical security applications.