Flexible wearable fabrics for solar thermal energy storage and release in on-demand environments

Efficient solar thermal energy storage and release via molecular solar thermal (MOST) fuels is essential to meet the ever-increasing global energy demands. However, most reported MOSTs still face some challenges, such as energy storage relying on ultraviolet (UV) light and solvent, and applications limited to room temperature. Herein, we propose a novel flexible wearable fabric consisting of azobenzene-containing dendrimers, polydopamine, and cotton fabric, which not only can efficiently store photon of ultraviolet, green, red light and sunlight energy but also enables applications in low- or room-temperature solvent-free environments. These remarkable properties are attributed to the red-shift of the n-π* band of the σ-fluoroazobenzene, the low glass-transition temperature of dendrimer fuel, and the photothermal effect of polydopamine. The storage energy density of the wearable fabric can reach 0.05 MJ kg−1 (18.2 kJ mol−1) accompanied by a storage half-life of up to approximately one month. Blue light-triggered heat release from wearable fabrics can increase the temperature by 11.1–12.3 °C, showing excellent results in room-temperature wrist guards and low-temperature body-warming applications. This work paves the way for the development of wearable fabrics for solar thermal energy storage and release in on-demand environments such as sunlight, solvent-free, and low temperature.