The colors of objects originate from reflection of light in certain directions and absorption of undesired light, producing substantial heating. Extensive efforts are expended to cool colorful objects to reduce their energy consumption. However, a strategy to cool colorful objects below ambient temperature while fully preserving their excellent color properties with high saturation and large viewing fields remains a significant challenge. Inspired by Morpho butterflies, we report a robust configuration consisting of a multilayer, disordered structure, and total reflection layer to cool colorful objects to overcome this challenge. Numerical simulations and experimental measurements demonstrated that our configuration can cool a class of colorful objects not only to a temperature of approximately 2°C below ambient temperature, but also with ultrahigh saturation (100%) and a wide range of viewing angles. These colorful cooling films have significant potential for energy sustainability in buildings, vehicles, facilities, and equipment.

Xinkun Zhao (State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University), Xiaoyuan Yan (College of Electronics and Information Engineering, Shenzhen University), Binbin Hong (College of Electronics and Information Engineering, Shenzhen University), Lei Sun (College of Electronics and Information Engineering, Shenzhen University), Wang Zhang (State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University), and Guo Ping Wang (College of Electronics and Information Engineering, Shenzhen University)

Wanlin Wang, Hongyun Xing, Xiaochi Shu, Xinkun Zhao, Xiaoyuan Yan, Binbin Hong, Lei Sun, Wang Zhang, and Guo Ping Wang, “Cooling colors below ambient temperature,” Optica 10, 1059-1066 (2023)