Effective temperature-regulating materials are essential for personal thermal comfort in challenging climatic conditions. Protonated covalent organic framework nanosheets (CONs), known for their high light absorption, low thermal conductivity, and enhanced processability, have been underexplored in this domain. Here, we present Janus-structured films with notable asymmetric photothermal properties and exceptional Joule heating capabilities, advancing personal thermal management strategies. By integrating protonated CONs and aramid nanofibers (ANFs) with opposite infrared reflectivity on either side of a conductive silver nanowires (AgNWs) film, the resulting CONs/AgNWs/ANFs film features a Janus architecture. This design maintains the CON-side temperature approximately 7 °C higher than bare skin, and 14 °C higher than the ANF-side under 0.5 sun irradiation, facilitating adaptable photothermal regulation. Additionally, the incorporation of AgNWs enables remarkable Joule heating capabilities, reaching saturation temperatures up to 195 °C within 15 s with input voltages ranging from 0.4 to 1.2 V. These Janus-structured films, with customizable photothermal properties and superior electrothermal performance, show significant promise for precise personal thermal management, facilitating controlled and comprehensive body temperature regulation.
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