Self‐Regulated Co‐Assembly of Janus Bilayer Films for Real‐Time Photothermal Imaging and Monitoring

Abstract Optimizing heat generation and diffusion in photothermal thin films is essential for developing advanced imaging systems that deliver high‐resolution and sensitive results. Herein, a self‐regulated co‐assembly strategy at the three‐phase interface is introduced for fabricating flexible, large‐area Janus bilayer films. These films consist of a well‐aligned silver nanowire monolayer and a densely packed gold nanoparticles@poly(methyl methacrylate) monolayer, exhibiting remarkable anisotropic properties in electrical conductivity and wettability. The films leverage reversible interactions, such as Au‐thiolate coordination and van der Waals forces, which enhance mechanical properties while providing wide working temperature range (−200 to 300 °C), self‐healability, and recyclability. By utilizing well‐assembled plasmonic superstructures for heat generation and transfer, the Janus film demonstrates exceptional photothermal sensitivity of less than 1 s for high steady‐state temperature of more than 60 °C under near‐infrared (NIR) irradiation, significantly improving the contrast and resolution of photothermal imaging. With these characteristics, the Janus film proves effective for high‐quality real‐time NIR imaging and monitoring of both stationary and moving objects, paving the way for advanced imaging strategies across diverse applications.