Solar Energy Storage Silks via Coaxial Wet Spinning

Near-infrared (NIR) radiation has widely been applied for phototherapy due to its beneficial thermal effect on human tissue. However, desirable thermal textiles have not been actualized by implementing this radiation into textile fiber. Herein, persistent NIR-emitting fibers have been fabricated by incorporating long-lasting phosphorescent phosphor and fluorescent Ag2S quantum dots (QDs) into the regenerated silk fibroin (SF)-based core–sheath fibers. Green-emitting phosphor was introduced into the fiber core during coaxial wet spinning, while various layers of QDs emissive in NIR range were deposited on the fiber surface. A double-layered hollow structure was obtained in these fibers with improved surface uniformity. Fluorescence spectrometry confirmed that the green emission of the embedded phosphors (i.e. 492 nm) was absorbed by the surface Ag2S layer to give continuous NIR emission. Up to 13.5 % of the 993 nm NIR radiation passed through porcine epidermis of 0.25 mm thickness. This work has shed new light on the fabrication of self-warming fiber, which is anticipated to be applied in various fields such as continuous warming textiles and wearable phototherapy devices.