Collaborative Research: Self-Assembled Multilayer Microsphere Particle Arrays as Engineered Photonic Structures for Sustainable and Energy-Efficient Radiative Cooling

About This Grant

Traditional air conditioning cooling is a human necessity and essential for society. However, it consumes a significant amount of energy and releases undesirable greenhouse gases. Passive daytime radiative cooling with engineered photonic structures is a promising sustainable and energy-efficient cooling technique. However, current photonic structures either require sophisticated, expensive, and hard-to-scale manufacturing processes to achieve precise material and structural control or have poor material and structural control with inexpensive, scalable manufacturing processes leading to inefficient and costly passive cooling. Research funded by this award looks to advance fundamental understanding and development of self-assembled architectures for new sustainable cooling technologies. In addition, the studied integrated design and manufacturing approach intends to be universally applicable to other photonic applications in broad wavelength ranges, such as structural coloration in the visible wavelength. The project’s multidisciplinary research activities intend to offer new perspectives in broad technology domains, including advanced manufacturing, optics, optoelectronics, semiconductors, heat transfer, and machine learning. Furthermore, this project looks to create new education and workforce development opportunities including transferable modular curricular and online lectures that are integrated into graduate and undergraduate courses across different disciplines, along with new hands-on demonstrations for a variety of outreach activities. Research completed by the project will employ a holistic, paradigm-shifting, and closed-loop approach of designing, manufacturing, and deploying multilayer self-assembled monolayer microsphere (MSMS) array architectures for passive daytime radiative cooling applications. In the MSMS structure, individual microspheres are self-assembled into a monolayer film of an ordered array, instead of random distribution. The particles can be from a large variety of materials, such as SiO2, TiO2, polymethyl methacrylate (PMMA), and others. Further, these self-assembled films will be stacked together with polymer films to form a multilayer structure for engineering optical response. The research team will integrate expertise in experimental self-assembly, photonic design and manufacturing optimization to achieve its objectives. Specific tasks include: (1) Universal self-assembly of particles based on a salt-assisted and acoustic self-limiting mechanism, whose manufacturing processes are automated with in-situ characterization systems and scalable through roll-to-roll systems; (2) Experiment-aware inverse design of structures based on a graphics-processing-unit-accelerated high-throughput semi-analytical rigorous-coupled-wave-analysis solver, which is further integrated with a machine learning-driven optimization of the manufacturing processes; and (3) Experimental demonstrations of passive daytime radiative cooling with the engineered photonic structures. In addition, the project studies processing-structure-property relationships and detection and mitigation of imperfections. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.