UV-Filtering Cellulose Nanocrystal/Carbon Quantum Dot Composite Films for Light Conversion in Glass Windows

The development of energy-saving materials in buildings based on biomass materials is a general consensus building construction of low-carbon cities. Herein, we reported an effective ultraviolet (UV)-filtered film, composed of carbon quantum dots (CDs) and cellulose nanocrystals (CNC). The results showed that CNC had nanoscale dimensions with a diameter of 20-50 nm and length of 250-450 nm, a high crystallinity index of 84.7%, and enrichment of hydrogen bonds on the surface. The photoluminescence spectra showed that lignin-based carbon quantum dots (CDs) exhibited a long-wavelength red emission (623 nm) and an uncommon narrow emission bandwidth (fwhm <30 nm). In addition, the prepared UV-filtered film had strong mechanical tensile properties, good UV light absorbing capability, and water resistance. The optical test showed that the film also had highly optical transparency (94%) and haze (70%). The excellent light management and conversion function of this film provides a new user experience for soft, uniform, healthy, and comfortable indoor sunlight lighting.