The discovery, published in January 2026 in the scientific journal ACS Applied Materials & Interfaces, focuses on a challenge in solar energy harvesting: capturing a broader range of sunlight and converting more of that energy into useful output. The researchers’ approach relies on microscopic structures called plasmonic supraballs, made by assembling numerous gold nanoparticles into larger spherical clusters.
Conventional photovoltaic solar cells convert sunlight directly into electricity. Their performance depends on the semiconductor materials they use, the wavelengths of light they can absorb, and the amount of energy lost through reflection, transmission, or heat.
Researchers have spent decades developing materials and structures that can improve light absorption and energy conversion. One promising avenue involves nanotechnology, which makes it possible to manipulate how light interacts with matter on extremely small scales.
A team led by researchers associated with Korea University’s KU-KIST Graduate School of Converging Science and Technology developed a new approach using gold nanospheres.
Rather than depositing individual nanoparticles randomly onto a surface, the scientists assembled them into larger, carefully organized spherical structures known as supraballs.
Each supraball contains numerous smaller gold particles. The resulting structures measure approximately 460 nanometers to 3 micrometers across, depending on how they are manufactured.
Although these dimensions are microscopic, the arrangement of the particles is crucial. Their collective interactions with light allow the structures to absorb a much broader range of wavelengths than a conventional film of gold nanospheres.
The innovation relies on a phenomenon called plasmonic resonance. When light interacts with metallic nanoparticles, electrons near their surfaces can oscillate collectively, concentrating electromagnetic energy in extremely small regions.
In the researchers’ supraballs, several optical effects work together. Localized surface plasmon resonances occur near the outer parts of the structures, while magnetic resonances associated with the arrangement of particles contribute to light absorption within their interiors.
These complementary mechanisms help the material absorb light across the visible and near-infrared portions of the solar spectrum.
Computer simulations and spectroscopic measurements showed that the supraball coatings could reach absorption levels exceeding 90% over parts of the measured spectrum.
Under standard AM 1.5G solar illumination conditions, the researchers reported an average absorption of approximately 88.8%, nearly twice that of the conventional gold nanosphere films used for comparison.
This distinction matters: the reported result concerns how effectively the coating absorbs incoming solar energy. It does not mean that a photovoltaic cell converts 88.8% of sunlight directly into electricity.
The ability to capture a broader range of wavelengths is especially interesting for technologies that exploit solar heat, including thermoelectric and photothermal systems.
To investigate whether the improved absorption could deliver a practical benefit, the researchers applied their supraballs to commercially available thermoelectric generator modules.
These devices work differently from ordinary photovoltaic cells. Instead of converting photons directly into electricity, they generate electrical power from a temperature difference between two sides of a thermoelectric material.
The scientists deposited the supraball coating from a liquid solution onto the surface of the generator modules. The process, known as drop-casting, did not require modification of the modules’ underlying structure.
When the coated devices were tested, the researchers observed a rapid response to illumination and stable operation under the experimental conditions.
Most importantly, the supraball-coated generator produced approximately 2.4 times the electrical power of a comparable generator coated with conventional gold nanospheres.
This represents a substantial improvement for the specific thermoelectric configuration tested. However, it is a relative comparison between two laboratory coatings, not a measurement of improved performance across all solar energy technologies.
The result therefore should not be interpreted as evidence that adding gold nanoparticles to an existing rooftop solar panel would multiply its output by 2.4.
One advantage of the approach is its manufacturing method. The gold nanoparticles can self-assemble into larger structures through a controlled process, and the resulting material can be deposited onto surfaces from a liquid solution.
This could simplify the production of light-absorbing coatings compared with some manufacturing methods requiring complex nanofabrication equipment.
The researchers also found that the structures retained strong optical absorption despite small imperfections in their internal arrangement, an encouraging property for future manufacturing.
However, several questions remain before the technology can be considered ready for commercial deployment. These include the cost of gold, large-scale production, long-term durability, and performance under actual outdoor operating conditions.
Future applications could include solar thermoelectric generators, photothermal systems, and hybrid photovoltaic-thermal devices that collect both electricity and useful heat.
Such systems could potentially make better use of portions of the solar spectrum that are not efficiently converted into electrical energy by conventional photovoltaic technologies.
For now, the findings represent a promising advance in solar energy harvesting rather than a ready-to-install improvement for commercial solar panels.
The experiment demonstrates how changing the microscopic arrangement of a familiar material can substantially alter its interaction with sunlight. By assembling gold nanoparticles into structured spheres, researchers achieved stronger absorption and a measurable increase in electrical output from a thermoelectric device.
Whether that performance can eventually translate into affordable, durable products remains to be determined. But the study offers a clear example of how nanomaterials could help future energy systems capture more of the sunlight already reaching Earth.

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