Multilayer Composite Structured Transparent Infrared-Selective Stealth Films with Synergistic Radiative Cooling.

Infrared-selective stealth films, which concurrently offer high visible transmittance, suppressed infrared emission, and selective thermal dissipation, have emerged as compelling candidates for infrared protection and thermal-target stealth. However, traditional multilayer architectures are predominantly designed through empirical trial-and-error protocols, which inherently hinder the synergistic optimisation of multiband spectral performance and yield suboptimal parameter-tuning efficiency. To circumvent this bottleneck, we introduce a reinforcement learning (RL)-driven multi-objective optimisation framework that automates the design of composite thin-film configurations. The optimised multilayer film structure consists of TiO2/ITO/Ag/ZnO/SiO2, with layer thicknesses of 180, 656, 10, 33.75 and 50 nm, respectively. Spectral characterisation reveals a weighted average visible transmittance of 79.77% over the 0.38-0.78 μm range, alongside blackbody-weighted average emissivities of 33.93%, 72.93%, and 19.94% in the 3-5, 5-8, and 8-14 μm bands, respectively. Consequently, the spectral profile exhibits high visible transparency, deep suppression of emissivity within the atmospheric windows (3-5 and 8-14 μm), and markedly elevated emissivity in the non-atmospheric band (5-8 μm). Analysis of the electromagnetic field distribution and power-loss density along the thickness direction reveals that the energy transmission and dissipation behaviours across distinct bands are synergistically governed by multilayer interference, interfacial multiple reflections, and lossy interlayer coupling mechanisms. Furthermore, angle-resolved infrared-emissivity analysis calibrated against the normal-incidence FDTD spectrum confirms that the structure retains robust polarisation adaptability and pronounced spectral selectivity at incidence angles up to 80°. The above results demonstrate the effectiveness of the reinforcement learning-driven optimisation framework for the automated co-design of multiband spectral responses. Moreover, the uncovered multilayer interference and loss-coupling mechanisms furnish a solid physical foundation for further performance refinement and rational design of transparent stealth coatings.