Zhou Yi, Lu Canhui, Xiong Rui
State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
ACS Nano. 2025 Feb 4;19(4):5029-5039. doi: 10.1021/acsnano.5c00330. Epub 2025 Jan 25.
Daytime radiative cooling (DRC) materials offer a sustainable, pollution-free passive cooling solution. Traditional DRC materials are usually white to maximize solar reflectance, but applications like textiles and buildings need more aesthetic options. Unfortunately, colorizing DRC materials often reduce cooling efficiency due to colorant sunlight absorption. Thus, this study reports a hierarchical photonic structure consisting of photoluminescent scatterer networks and a nanocellulose cholesteric structure. This design effectively addresses the trade-off between cooling efficiency and coloration, achieving enhanced cooling through synergistic all-day coloration. Sustainable nanocellulose with highly ordered cholesteric structures selectively reflects visible wavelengths, generating structural color and high mid-infrared (MIR) emission. The photoluminescent scatterer networks enhance reflectance and convert absorbed light into photoluminescent emission, further promoting cooling. This synergistic photonic interaction results in a significantly enhanced high reflectance of 92%, high MIR emissivity of >90%, stable and tunable structural color appearance, and hours-long afterglow photoluminescence. Consequently, a subambient cooling of up to 11.3 °C under sunlight is attainable, accompanied by the ability to produce programmable structural color and photoluminescent patterns for daytime and nighttime visibility. The enhanced cooling efficiency achieved through the synergistic interplay of four optical mechanisms from the UV to MIR region offers a promising design paradigm for other DRC materials.
日间辐射冷却（DRC）材料提供了一种可持续、无污染的被动冷却解决方案。传统的DRC材料通常为白色以最大化太阳反射率，但纺织品和建筑等应用需要更多美观的选择。不幸的是，给DRC材料着色往往会因着色剂吸收太阳光而降低冷却效率。因此，本研究报告了一种由光致发光散射体网络和纳米纤维素胆甾相结构组成的分级光子结构。这种设计有效地解决了冷却效率和颜色之间的权衡，通过协同的全天着色实现了增强的冷却效果。具有高度有序胆甾相结构的可持续纳米纤维素选择性地反射可见波长，产生结构色和高中红外（MIR）发射。光致发光散射体网络增强了反射率，并将吸收的光转化为光致发光发射，进一步促进冷却。这种协同的光子相互作用导致显著增强的92%的高反射率、>90%的高MIR发射率、稳定且可调的结构色外观以及长达数小时的余辉光致发光。因此，在阳光下可实现高达11.3°C的低于环境温度的冷却，同时具备产生可编程结构色和光致发光图案以实现白天和夜间可见性的能力。通过从紫外到中红外区域的四种光学机制的协同相互作用实现的增强冷却效率为其他DRC材料提供了一种有前景的设计范例。
