Gold Supraballs Nearly Double Solar Absorption, Tapping Full Solar Spectrum

Scientists are actively seeking novel materials to enhance solar energy harvesting by absorbing light across the full solar spectrum. While current gold and silver nanoparticles (NPs) are cost-effective, their primary absorption in visible wavelengths limits overall efficiency.

Innovating with Self-Assembling Gold Supraballs

To address this challenge, researchers Jaewon Lee, Seungwoo Lee, and Kyung Hun Rho have proposed an innovative solution: self-assembling gold supraballs. These unique structures consist of gold nanoparticles that aggregate to form small spheres. The diameter of these supraballs was meticulously optimized to maximize the absorption of sunlight wavelengths, critically including near-infrared light.

Design Optimization Through Computer Simulations

The development process began with advanced computer simulations. These simulations were instrumental in optimizing the supraball design and predicting the performance of films made from these structures. Initial models indicated that the optimized structures should absorb over 90% of sunlight wavelengths.

Demonstrating Enhanced Performance

Following the successful simulations, a physical film of gold supraballs was developed. This was achieved by simply drying a solution containing the structures onto a commercially available thermoelectric generator (TEG), a device that converts light energy into electricity. This straightforward process was conducted under ambient room conditions.

Demonstrations using an LED solar simulator revealed remarkable results. The supraball-coated TEG achieved an average solar absorption of approximately 89%. This figure represents a near doubling of the absorption rate compared to a TEG coated with a conventional film of single gold NPs, which recorded only 45%.

"The plasmonic supraballs provide a straightforward method for harvesting the full solar spectrum," stated Seungwoo Lee. "This coating technology could significantly reduce barriers for high-efficiency solar-thermal and photothermal systems in practical energy applications."

Funding Acknowledgments

This research received funding from the National Research Foundation of Korea, the Korea Institute of Science and Technology Institutional Program, the Korea-US Collaborative Research Fund, and a Korea University grant.