Colored textiles based on noniridescent structural color of ZnS@SiO2 colloidal crystals for daytime passive radiative cooling

Abstract

Passive radiative cooling (PRC) technology, which utilizes the optical properties of materials to achieve electricity-free and spontaneous cooling, holds great promise for energy conservation and combating global warming. Integrating PRC with textiles enables precise regulation of the microclimate of the human body, facilitating sustainable and effective individual thermal comfort. However, such PRC materials typically exhibit a white or mirror-like appearance to minimize solar energy absorption, severely limiting their aesthetic appeal and practical application in real-life scenarios. Herein, we present a colored textile for PRC by employing the spray coating method with noniridescent structural color pigments consisting of carbon-modified ZnS@SiO2 core–shell microspheres (colloidal crystals). This approach simultaneously achieves noniridescent colors and efficient cooling. By using the photonic properties of ZnS and the core–shell structure, the ZnS@SiO2 colored textile selectively reflects visible light, resulting in coloration while reducing solar absorption. Furthermore, the phonon resonance (Fröhlich mode) of the SiO2 shell ensures high emissivity of the ZnS@SiO2 colored textile within the atmospheric window, allowing for substantial radiative heat dissipation. Outdoor experiments demonstrate that both the green and amaranth ZnS@SiO2 textiles could lower the simulated skin temperature by 5 ∼ 6 ℃ in direct sunlight, compared to ZnS and dye textiles of the same hue. Additionally, the ZnS@SiO2 colored textiles also exhibit excellent softness, washability, hydrophilicity, breathability, and tensile properties, making them suitable for practical applications. This work not only provides a practical method for synthesizing noniridescent structural color pigments with high color saturation but also offers new insights into the design of colored passive radiative cooling textiles.