Cellulose nanocrystal-templated synthesis and distribution of carbon dots to construct covalent networks with enhanced photostability for light management applications.

Carbon dots (CDs) suffer from poor photostability in light-conversion applications, as physical encapsulation fails to suppress photo-oxidation due to weak interfacial interactions. To address this, a covalent interface engineering strategy is developed to induce the in situ synthesis of CDs on cellulose nanocrystals (CNC) as a template. Via one-step amidation and silylation, a covalently grafted network structure, CNC-templated CDs (CNC-CDs), is constructed, which suppresses aggregation-induced quenching and enhances the solid-state quantum yield of CDs from 1.67% to 10.08%. CNC-CDs utilize a CNC framework to promote electron transfer and suppress electron-hole recombination by adjusting the band structure, thereby reducing the generation of singlet oxygen. The resulting CNC-CDs/PVA film integrates spectral conversion (from CDs) and light scattering (from CNCs), leading to a 10.43% increase in red-light photon flux density and a 24.2% enhancement of the Hill reaction rate in isolated chloroplasts. Lettuce cultivation shows that covering plants with this film increases fresh weight by 23.41% and dry weight by 18.91%. This study provides a new interfacial design strategy for highly stable, multifunctional light-conversion materials.