Enhanced biological photosynthetic efficiency using bio-based dual-emissive sandwich structure films via wrapping of carbon dots for precise spectral conversion

Improving photosynthesis and light capture using bio-based light-conversion films increases crop yield and paves a sustainable way to meet the growing global food demand. In this study, red-emissive carbon dots (RCDs) and blue-emissive CDs (BCDs) were trapped in biopolymers to develop a novel dual-excitation dual-emission light-conversion film (BRLCFs) with sandwich structure for efficient solar spectral conversion and promote photosynthetic efficiency of greenhouse plants. The middle layer of the film comprises polyvinyl alcohol (PVA), RCDs, and ascorbic acid (AA), which convert ultraviolet and green light into red light. The strong hydrogen bonding between the RCDs and PVA, including the antioxidant properties of AA, ensured excellent stability of the red light emission of the film. The edge layers, which composed of cellulose acetate and BCDs, converted ultraviolet light into blue light. This composition allowed the film to maintain exceptional photostability and morphological stability, even in high-humidity environments. In agricultural cultivation, BRLCFs significantly enhanced lettuce growth parameters, with a notable 21.89 % increase in fresh weight and 19.54 % increase in dry weight, highlighting the potential of BRLCFs to boost crop yield in controlled environments.