Scalable dual-layer film with broadband infrared emission for sub-ambient daytime radiative cooling

• Published in: Solar energy materials and solar cells 2020-05, Vol.208, p.110393, Article 110393
• Main Authors: Meng, Sheng, Long, Linshuang, Wu, Zuoxu, Denisuk, Nicholas, Yang, Yue, Wang, Liping, Cao, Feng, Zhu, Yonggang
• Format: Article
• Language: English
• Subjects: Broadband; Broadband emission; Cooling; Cooling effects; Corrosion prevention; Daytime; Daytime radiative cooling; Dual-layer film; Durability; Emission analysis; Energy conservation; Fabrication; Infrared spectra; Irradiation; Passive cooling; Polymers; Polyvinyl fluoride; Polyvinyl fluorides; Radiation; Ray tracing method; Selective emission; Silver; Sub-ambient cooling; Temperature
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2020.110393

As a passive cooling method with no energy input, radiative cooling has great potential in applications like building energy saving. The key to effective radiative cooling lies in selectively controlling the radiative properties in both solar and mid-infrared spectrums, and simple structures based on polymer materials attract growing attentions due to their overwhelming advantages of low cost and large-scalable fabrication. In this study, a dual-layer film consisting of polyvinyl fluoride (PVF) layer and Ag coating is proposed to act as an efficient daytime radiative cooler with low solar absorption and broadband infrared emission. An outdoor test demonstrates that sub-ambient daytime cooling is successfully achieved by the proposed cooler with an equilibrium temperature 2 °C below the ambient under solar irradiation of 950 W/m2. Due to better durability and better performance in anti-staining and corrosion protection than other polymer materials, the demonstrated cooling performance based on the PVF film would facilitate radiative cooling principle in much broader applications. •Broadband radiative cooler based on PVF film for daytime cooling.•Simple structure with dual layers of PVF and Ag coating.•Low cost, scalable-manufactured, durable, and anti-staining.•Experimental performance of 2 °C lower than ambient under direct sunlight.•Theoretical performance close to ideal broadband emitter.