Modular Dynamic Anti‐Counterfeiting Based on the In‐Situ Host‐Guest Interactions Induced Full‐Color Room Temperature Phosphorescence

The inherent instability of triplet exciton transitions in carbon dots (CDs) is a major obstacle to achieving room‐temperature phosphorescence (RTP) in their composites. Herein, sustainable hydrolyzed lignin is utilized to synthesize F, N co‐doped carbon dots (FNLCDs). Subsequently, a facile cross‐linking strategy is adopted to fabricate composites that exhibit excellent dual RTP and fluorescence emission through amide linkages and hydrogen bonding between FNLCDs and melamine. This tactic effectively modulates intersystem crossing, enabling precise regulation of both the RTP lifetime (up to 1443.3 ms at 480 nm) and the singlet–triplet energy gap (ΔE ST ). Moreover, a series of color‐ and shape‐tunable dual‐emissive composites is further assembled into “Lego‐like” modules for multi‐level dynamic information encryption. This work thus broadens the scope of application for biomass‐derived carbon materials. It also provides a universal and effective method for engineering them toward advanced time‐ and shape‐resolved anti‐counterfeiting technologies.