Thermal Management to Break the Heat Trap: Scalable Lithography-Free Multilayer Films for Radiative Cooling

This work presents a high-performance, lithography-free multilayer absorber/emitter for passive radiative cooling. The proposed structure exhibits a strong absorption resonance around 9 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathbf{m}$</tex>, aligning with the atmospheric transparency window to maximize thermal emission. The structure achieves a temperature reduction of −10.93°C at 20°C ambient temperature under purely radiative cooling conditions <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(h_{c}=0\mathbf{W}/\mathbf{m}^{2}\mathbf{K})$</tex>. As convective heat transfer increases, the cooling effect remains strong, reaching 6.68°C for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$h_{c}=3 \mathbf{W} / \mathbf{m}^2 \mathbf{K}$</tex> and 11.30°C for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$h_{c}=6 \mathbf{W} / \mathbf{m}^2 \mathbf{K}$</tex>. The proposed scalable, cost-effective, and fabrication-friendly approach represents a significant advancement in energy-efficient cooling technologies for industrial and thermal management applications.