Ultrafast Laser-Engineered Hierarchical Interface for Synergistic Radiative Cooling and Droplet Energy Harvesting

Abstract Passive daytime radiative cooling provides an energy-free approach for thermal management, but achieving multifunctional operation under realistic outdoor conditions remains challenging, because optical regulation, surface wetting, and energy conversion are typically realized with separate material components. Here, we develop a femtosecond laser-engineered passive radiative cooler (FLA-PRC) based on a hierarchical PTFE/Ag/SiO2 interface that simultaneously regulates photons, water droplets, and interfacial charges. Orthogonal laser scanning creates periodic flat-topped micropyramid arrays decorated with secondary micro/nanostructures, enabling synergistic control of solar scattering, infrared emission, and superhydrophobicity. Combined spectral measurements and FDTD simulations reveal that the laser-induced hierarchical morphology enhances solar light redistribution through multiscale scattering while promoting mid-infrared coupling and emission through increased optical interaction pathways. The Ag layer further integrates broadband solar reflection with electrostatic induction for droplet energy harvesting. This work establishes a deterministic laser-fabricated interface strategy for coordinating photonic, wetting, and electrical functions within a single-surface architecture.