All-biomass tunable CPL films based on cellulose nanocrystals and Taxus carbon dots for multimodal...

Cellulose-based fluorescence carbon dots (CDs) hybrid materials exhibiting multiple optical states hold significant promise for advanced information encryption and anti-counterfeiting applications. However, constructing all-biomass circularly polarized luminescence (CPL) with tunable optical states to substantially enhance anti-counterfeiting performance remains a challenge. Herein, a doping-free, one-pot hydrothermal method was developed to simultaneously synthesize blue-and red-emitting biomass carbon dots (B-BCDs and R-BCDs) using natural Taxus leaves as carbon sources. Subsequently, all-biomass CPL films with tunable emission were fabricated through an evaporation-induced self-assembly (EISA) strategy, incorporating B/R-BCDs into eco-friendly chiral cellulose nanocrystals (CNC) matrices. The obtained all-biomass CPL films simultaneously displayed vivid structural colors with a blue-to-yellow transition and tunable multicolor fluorescence under UV irradiation. Ultrasonication treatment modulated the photonic bandgap (PBG) of CPL films, enabling tunable CPL emissions at 450 nm and 670 nm. Importantly, dual regulation of both the fluorescence from the BCDs and the structural color form the CNCs was achieved by leveraging the spectral overlap between the modulated PBG and the emission wavelengths of the BCDs. Furthermore, advanced information encryption and anti-counterfeiting applications were demonstrated based on the multimodal luminescence properties of these films.