Plasmonic Supraballs for Scalable Broadband Solar Energy Harvesting

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Effective solar energy harvesting requires absorbers with large-area scalability and broad light absorption from visible to near-infrared (NIR) wavelengths.
• Conventional materials often struggle to balance scalability with strong light-matter interactions across the solar spectrum.

Purpose of the Study:

• To introduce plasmonic colloidal supraballs as a solution-processable platform for enhanced broadband solar energy harvesting.
• To investigate the light absorption properties and practical utility of these supraballs in solar energy conversion devices.

Main Methods:

• Fabrication of gold nanosphere (Au NS) supraballs using confined colloidal self-assembly, allowing tunable diameters.
• Characterization of supraball absorption spectra using numerical simulations and Fourier-transform infrared spectroscopy.
• Integration of supraballs onto commercial thermoelectric generator (TEG) modules for performance evaluation.

Main Results:

• Supraballs exhibit synergistic light trapping via localized surface plasmon resonances (LSPRs) and Mie-type magnetic resonances, achieving >90% absorption across the solar spectrum.
• Average solar absorption of supraball films reached ~88.8% under AM 1.5G illumination, nearly double that of conventional Au NS films.
• Supraball-coated TEGs demonstrated stable operation, rapid photoresponse, and a 2.4-fold increase in power output compared to controls.

Conclusions:

• Plasmonic supraballs represent a scalable, solution-processable class of absorbers bridging nanoscale plasmonics with macroscopic solar energy harvesting.
• This technology offers a promising pathway for next-generation solar thermoelectric, photothermal, and thermal management applications.
• The developed supraballs significantly enhance solar energy conversion efficiency in practical devices.