By using gold nanospheres engineered to capture light across the solar spectrum, researchers at Korea University took a step toward lowering barriers to more efficient and cost-effective renewable energy harvesting.
Hun Rho et al. introduce plasmonic colloidal supraballs — solution-processable assemblies of gold nanospheres — as a robust and versatile platform for broadband solar energy harvesting. Image credit: Hun Rho et al., doi: 10.1021/acsami.5c23149.
Scientists are exploring materials that absorb light across the solar spectrum to improve solar energy harvesting.
Gold and silver nanoparticles have been suggested as a solution because they’re easy and cost-effective to make, but current nanoparticles’ light absorption is confined to visible wavelengths.
To capture additional wavelengths, including near-infrared light, Korea University researcher Seungwoo Lee and colleagues propose using self-assembling gold supraballs.
These structures consist of gold nanoparticles that clump together and form tiny spheres.
The diameter of the supraballs was adjusted to maximize the absorption of wavelengths present in sunlight.
The researchers first used computer simulations to optimize the design of individual supraballs and to predict the performance of supraball films.
The results from the simulations showed that the supraballs should absorb more than 90% of wavelengths from sunlight.
Next, the scientists created a film of gold supraballs by drying a liquid solution containing the structures on the surface of a commercially available thermoelectric generator, a device that converts light energy into electricity.
The films were created in ambient room conditions — no clean rooms or extreme temperatures required.
In demonstrations with an LED solar simulator, the supraball-coated thermoelectric generator had an average solar absorption of about 89%, nearly twice that of a thermoelectric generator with a conventional film made from single gold nanoparticles (45%).
“Our plasmonic supraballs offer a simple route to harvesting the full solar spectrum,” Dr. Lee said.
“Ultimately, this coating technology could significantly lower the barrier for high-efficiency solar-thermal and photothermal systems in real-world energy applications.”
The team’s work appears in the journal ACS Applied Materials & Interfaces.
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Kyung Hun Rho et al. 2026. Plasmonic Supraballs for Scalable Broadband Solar Energy Harvesting. ACS Appl. Mater. Interfaces 18 (1): 2523-2537; doi: 10.1021/acsami.5c23149
