Multicolor circularly polarized luminescence from chiral carbon dots and cellulose nanocrystals assemblies for visual polarization detection

Chiral carbon dots (CCDs) combined with outstanding photoluminescence and unique chirality have become intriguing carbon-based nanomaterials, however, the realization of the optical activity in both ground and excited states remains a great challenge. To overcome this difficulty, multicolor CCDs have been synthesized by changing surface oxidation states and P atom doping via solvothermal route, which emit unusual near-ultraviolet, and blue, yellow and red fluorescence with high photoluminescence quantum yields (PLQY) of 28.99%, 22.55%, 84.63%, and 75.73%, respectively. Benefiting from the excellent luminescence of CCDs and chiral environment of cellulose nanocrystals (CNCs), a series of CCDs@CNCs composite films were produced by matrix-assisted method. The electrostatic, H-bonds and vdWs interactions are found to drive the formation of co-assembly and facilitate the chiral transfer and amplify between CNCs and chromophores. Thus, the CCDs@CNCs films display bright and multicolor right-handed circularly polarized luminescence (CPL) with extremely high luminescence dissymmetry factor (glum) values of −0.24 to −0.90. The synergy of intense glum and high efficiency of multicolor composite films endow them with a potential for visual polarization detection. This research provides inspiration and feasibility for constructing CPL-active materials in co-assembly system and harvesting high glum value.