A Dual-Selective Electrospun Film Further Harnessing Atmospheric Windows for Daytime Passive Radiative Cooling

Passive radiative cooling, which dissipates heat to outer space (∼3 K) through the atmospheric transparency window (ATW), has attracted significant attention due to its potential for subambient cooling. The key feature of radiative cooling materials lies in their high emissivity within the atmospheric transparent window. Current material designs primarily focus on either broadband high emissivity or selective emitters dominated by the 8–13 μm range (defined as the first ATW). However, another band of the ATW is frequently overlooked (defined as the second ATW), leaving its cooling potential underutilized. Herein, we fabricate a dual-selective radiative cooling film (DS-F) composed of poly(ethylene oxide) (PEO) and polytetrafluoroethylene (PTFE) via electrospinning, demonstrating exceptional daytime radiative cooling performance. The molecular vibrations of PEO and PTFE synergistically contribute to achieving an infrared emissivity of 94.2% in the first atmospheric transparency window (8–13 μm) and 66.5% in the second window (16–25 μm). The micronanostructured fibrous architecture endows the film with a remarkable solar reflectance of 94.8%. Consequently, the DS-F achieves a subambient temperature reduction of 10.3 °C, outperforming both single-selective and nonselective radiative coolers. Numerical simulations under arid climate conditions reveal an effective cooling performance of 4.99 °C, suggesting promising potential for broader applications of dual-selective thermal emitters in energy-efficient cooling technologies.