MAE researchers fight climate change with roll-to-roll manufacturing method

An MAE doctoral student published a research paper in late July addressing sustainability in the fabrication and use of scalable microstructure photonic coatings and it was recently included in the September issue of the American Chemical Society’s (ACS) Nano Letters publication.

Sipan Liu is a member of Assistant Professor Jong Eun Ryu‘s research group and was one of the primary writers on the aforementioned paper, titled “A Scalable Microstructure Photonic Coating Fabricated by Roll-to-Roll ‘Defects’ for Daytime Subambient Passive Radiative Cooling.”

To conduct this research, Liu and Dr. Ryu’s research group collaborated with several individuals from multiple universities and other institutions – prominently including Chenxi Sui from Duke University. 

The authors’ goal was to address climate-related challenges with building cooling systems by exploring the means of producing passive radiative cooling (PRC) materials, which can mitigate cooling consumption by delivering wireless access to the cold thermodynamic resources, to assist these systems in being more energy efficient, cost-effective and environmentally friendly. 

“Climate change has severely impacted people’s lives and the environment. Due to the rising temperature, approximately 20.3% of electrical energy was used in the building cooling system for the US residence and commercial buildings, presenting a challenge toward a sustainable future,” the paper’s abstract states. “By reflecting solar radiation and radiating heat into the cold universe through the atmospheric transparent window, the radiative cooling materials can achieve noticeable cooling energy savings under direct sunlight. “

The issue then, at least for Ryu’s research group, becomes how to produce the strict photonic microstructures needed to produces these materials while maintaining manufacturing scalability. 

To address this, Liu and other researchers from Ryu’s research group developed a rapid, low-cost, template-free roll-to-roll method to fabricate spike microstructured photonic nanocomposite coatings that shows a radiative cooling power of 39.1 W/m2. The method indicates a potential 14.4% cooling energy-saving capability across the United States while paired with the coating’s superhydrophobic and contamination resistant qualities. 

“Our roll-to-roll manufacturing demonstrates a real building-level scale method to fabricate microstructure photonic coating,” Liu said. “This fabrication method is adaptable to a wide range of viscous composite pastes, enabling the scalable application of photonic coatings. The findings of this research not only serve as inspiration for technological advancements in radiative cooling materials but also promising platform for expanding the application of traditional roll-to-roll fabrication.”

To learn more about this research and read the paper in its entirety, visit the publication’s website.