题 目：Optical metamaterial for large scale day-time radiative cooling
报告人：Xiaobo Yin 教授，科罗拉多大学博尔德校区
时 间：6月2日（周五 ），上午10:30-11:30
Passive radiative cooling draws heat from a room-temperature object’s surface and radiates it into col sky in form of infrared radiation to which the atmosphere is transparent. Nanophotonic structures that fully reflect solar irradiance while emit strongly infrared radiation were recently introduced for effective day-time radiative cooling[1-3]. Given the intrinsic low power density of emitted infrared radiation, however, practical radiative cooling applications demand scalable manufacturing capability of these judiciously designed photonic structures. Recently we have developed a scalably manufactured metamaterial for effective radiative cooling using a random glass-polymer metamaterials, achieving an infrared emissivity greater than 0.93 across the entire atmospheric window while being fully transparent to the solar spectrum, approaching the theoretical limit for day-time radiative cooling. The 300-mm-wide metamaterial was fabricated with a roll-to-roll process at a 5-meter-per-minute output rate. The noon-time (11am –2pm) radiative cooling effect has been demonstrated with an average cooling power of 93 W/m2 under direct sunshine during a continuous three-day field test. The 72-hr average cooling power is greater than 110 W/m2. The scalably manufactured metamaterial shows its potentials in large scale cooling applications, such as cooling roof and cooling solar cell panels to improve solar cell efficiency .
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 Y. Zhai, Y. G. Ma, S. N. David, D. L. Zhao, R. N. Lou, G. Tan, R. G. Yang, X. B. Yin, “Scalable-manufactured Randomized Glass-Polymer Hybrid Metamaterial for Day-time Radiative Cooling”, Science (2017).
Dr. Xiaobo Yin received his PhD from Stanford University in 2008 and is currently an Assistant Professor of Mechanical Engineering at the University of Colorado Boulder. His research focuses on nanophotonics and nanomaterials, optical and acoustic metamaterial, and scalable manufacturing. He authored and co-authored more than 60 journal publications with 1,800 citations annually. His works have been featured on numerous media outlets including Physics Today, Scientific American, the Economists, and Forbes.