Enhanced photothermal performance of dielectric silicon attached with multiple plasmonic gold nanoparticles

Abstract The photothermal properties of dielectric materials at the nanoscale have garnered significant attention, especially in fields such as optical heating, photothermal therapy, and solar utilization. However, although dielectric materials can concentrate and manipulate light at the nanoscale, they cannot provide sufficient photothermal efficiency in a direct absorption solar collector. Combining plasmonic metal nanoparticles with dielectric nanostructures enables the fabrication of hybrid nanomaterials with excellent photothermal performance. This study presents a novel approach involving uniformly adhering plasmonic gold nanoparticles onto dielectric silicon nanoparticles to enhance the absorption peak, leading to a substantial enhancement of photothermal conversion efficiency. The results demonstrate that the absorption peak of silicon-gold hybrid nanoparticles exceeds that of pure silicon nanoparticles, achieving a 38% increase in photothermal conversion efficiency within a 10 ppm aqueous solution under a 20 mm optical path. The coupling of localized surface plasmon resonance and quadrupole resonance effects enhances the electric field, causing a temperature rise in both the hybrid nanoparticles and the surrounding aqueous solution. Nanostructural modulation studies reveal that the photothermal efficiency of silicon-gold hybrid nanoparticles is positively correlated with gold nanoparticle size but negatively correlated with silicon nanoparticle size. Combining multiple plasmonic nanoparticles with dielectric materials can effectively enhance photothermal performance and hold great application potential in direct absorption solar collectors and solar thermal utilization.