Flexible Solar Thermal Fuel Devices: Composites of Fabric and a Photoliquefiable Azobenzene Derivative

Controllable storage and release of solar energy has always been a highlighted scientific issue for its benefit of mankind. Solar thermal fuels (STFs) supply a closed cycle and renewable energy-storage strategy by transforming solar energy into chemical energy stored in the conformation of molecular isomers, such as cis/trans-azobenzene, and releasing it as heat under various stimuli. Although the potential high energy density of the STFs which are based on the hybrids of azobenzene derivatives and carbon nanomaterials has been reported the solvent-assistant charging hinders their practicability. In this study, a solid-state STF device is designed and fabricated by compositing one photoliquefiable azobenzene (PLAZ) derivative with a flexible fabric template. The photoinduced phase transition of the PLAZ derivative enables the charging of the flexible STFs to be totally solvent-free. Interestingly, the energy-storage capacity (energy density approximate to 201 J g(-1)) of flexible PLAZ STFs has been improved by the soft fabric template. The exothermic situation is monitored with one infrared camera, which shows 4 degrees C temperature difference between charged and discharged samples under blue light stimulus. The flexible STFs are may be used in practice as heating equipment.