Spherical Plasmonic Structures for Solar Absorption

Direct Solar Absorption Collectors explore the thermo-optical properties of different absorber fluids to convert solar radiation into thermal energy. Colloids of metallic nanoparticles (or nanofluids) have shown a high potential to convert solar radiation into thermal energy efficiently; it is due to the possibility to tune the plasmon resonance next to the near infrared region and a high thermal conductivity coefficient. Different complex structures such as triangles, pyramids, octahedral, hollow-structure have been proposed theoretically for this purposes; however, to synthesize this kind of nanoparticles is not a straightforward method, requiring strong reducing agents and usually, a broad particle polydispersity is obtained. In this work, using a full-wave field numerical model, we study the solar absorption of metallic nanofluids composed of only spherical structures, which are expected to be more stable and which is the most natural NP geometry to be synthesized chemically. Solid, shell and multilayered spherical particles, as well as, a pair of spheres are analyzed. The values of solar radiation absorber condition for a pair of spheres and Multilayered particles are more significant than the obtained with spherical structures.