Optically Switched and High-Energy Azobenzene-Based Wearable Solar Thermal Fabrics for Effective Body Temperature Regulation

Photoisomeric azobenzene-based phase-change storage materials (AZO-PCMs)/polymer fabrics have garnered significant interests for solvent-free and photocontrolled phase transition storage applications. Nevertheless, high molecular weight and low thermal conductivity of polymer fabrics lead to restricted energy and power density. Here, optically switched and high-energy wearable solar thermal fabrics (STFs) are developed by templating different AZO-PCMs to functionalized carbon nanofiber cloth (FCFC). Thereinto, the AZO-PCMs are utilized as photocontrollable phase-change energy storage materials, while the FCFC is applied as a flexible, high thermal conductivity, and low-mass substrate to further significantly improve the energy storage capacity by enhanced intermolecular interactions (particularly the H-bonds) and achieve rapid heat release under visible light excitation. By optimizing the molecular structure, loading capacity, and photoexcitation condition, a high energy density of 58.44 Wh kg⁻¹ and a high thermal conductivity of 3.13 W m⁻¹ K⁻¹ can be obtained. Surprisingly, a high power density of 1402.56 W kg⁻¹ is implemented under green light, which is 3420 times as much as that by spontaneous heat release in the dark, showing an effectively light-actuated heat release. Moreover, the excellent bending, long-cycling stability, and large temperature rise of this wearable STFs have been proved for effective body temperature regulation.