Core-tailored carbon dots with ultrabroadband dynamic afterglow for highly secure data encryption and anticounterfeiting

Carbon dots (CDs) with ultra-broadband and time-dependent afterglow photoluminescence (PL) are pivotal for next-generation anti-counterfeiting and dynamic information encryption, yet their rational design remains a formidable challenge in terms of spectral-temporal tunability and mechanistic clarity. Herein, we propose a molecular engineering strategy to synthesize CDs@B 2 O 3 via a one-step fusion heating process, using levofloxacin and 1-pyrenylboronic acid as the carbon source precursors within a boric acid matrix. By properly modulating the electronic state distribution between the green-emitting surface states and the red-emitting core states of the CDs, we achieve full coverage of the visible spectrum from green to the near-infrared region. Mechanistic investigations reveal that the broadband afterglow arises from the synergistic delayed fluorescence (DF) of N-heterocyclic surface molecular states and large conjugated domains that activate red core states. Notably, the increased conjugation degree of the carbon core in L,P-CDs@B 2 O 3 results in a higher proportion of red-emitting states and longer afterglow time, enabling a unique color-changing afterglow that transitions from an initial green through yellow and finally to red within 1 s. The time-resolved afterglow characteristics facilitate high-capacity graphical anti-counterfeiting, demonstrating promising applications in graphical security and information storage with spatiotemporal resolution. These findings not only provide an effective approach for designing smart afterglow nanomaterials but also elucidate the structure-emission relationship in carbon-based systems, offering insights into the rational engineering of multi-modal photoluminescent materials.