In situ wrapping carbon dots towards robust, durable and transparent tri-layer films with precise spectral conversion and excellent self-cleaning properties

To boost agricultural productivity and pave an eco-friendly way to solve the global food crisis, light conversion agents with spectrum matching, and high stability are promising candidates. Carbon dots (CDs) are regarded as viable nanomaterials for light conversion based on their unique physical and optical properties, particularly those that can mitigate aggregation-caused quenching (ACQ). Here, a series of polymer wrapped CDs, that overcome the ACQ and emit intense red-light in solid-state, were synthesized. Notably, the quantum yields of these solid-state CD-polymers are improved to 20.91%. Then a light conversion (LC) layer on polyethylene (PE) film using CD-polymers was directly generated, owing to the film-forming characteristics of polymers. Furthermore, a superhydrophobic coating, which is composed of polydimethylsiloxane (PDMS) and hydrophobic fumed silica, was constructed and connected with the LC layer via a PDMS intermediate layer. The transparent, UV-to-red light conversion and superhydrophobic self-cleaning multi-layers on PE (LCSHL-PE) were eventually produced. The water contact angle of the LCSHL-PE film is as high as 174(degrees) and the water rolling angle is less than 2(degrees). In comparison to PE film, the LCSHL-PE can enhance red light irradiance by 9.44% while decreasing UV irradiance by 41.21%. More importantly, the obtained LCSHL-PE film displays outstanding mechanical robustness and weather durability, which would ensure its potential in agricultural applications.