Tunable and Responsive Circularly Polarized Luminescence of Self-Organized Cellulose Nanocrystal Chiral Superstructures Loaded with AIE Luminogen

Abstract

Circularly polarized luminescence (CPL) holds great potential for next-generation display techniques. However, dynamic, multicolor CPL with high luminescent quantum yield (PLQY) and tunable dissymmetry factor (g_lum) based on cost-effective, sustainable materials is scarcely attainable. Herein, a straightforward approach is proposed for engineering cellulose nanocrystal (CNC) chiral superstructures loaded with aggregation-induced emission luminogens (AIEgens) through the evaporation-induced self-assembly of renewable CNCs and tetra-(4-pyridylphenyl)ethylene molecules. The judicious design of two building blocks as chiral donor–acceptor pairs not only respectively achieves an 86-fold and 2.1-fold improvement in the PLQY of resulting systems in the suspension and aggregate states in comparison with bare AIEgens, but also endows AIEgen-loaded CNC chiral superstructures with pH-tunable, humidity-responsive, multicolor CPL with a maximal |g_lum| of 0.89. It is revealed that chiral induction and photonic bandgap effects—which are dominated by chiral donor–acceptor interactions and homogeneous or heterogeneous self-assembly processes—are involved in CPL mechanisms. Finally, humidity-responsive multiple changes (structural color, fluorescent color, CPL) are realized in both biobased inks and films, which is of paramount importance for potential applications in multicolor dynamic display and information encryption. This work offers the underlying insights for the construction of cost-effective, renewable superstructures with dynamically tunable CPL.