Black Silver: Three-Dimensional Ag Hybrid Plasmonic Nanostructures with Strong Photon Coupling for Scalable Photothermoelectric Power Generation.

The conversion of solar energy into electric power has been extensively studied, for example, by photovoltaics. However, photo-thermoelectric (P-TE) conversion as an effective solar-to-electricity conversion process is less studied. Here, we present an efficient full-solar-spectrum plasmonic absorber for scalable P-TE conversion based on a simple integration of light absorber and commercial thermoelectric modules. Our developed light absorber of silica-silver hybrid structures achieves an average absorption of 99.4% in the wavelength range from 200 to 2500 nm, which covers over 98% solar energy in this range. It thus appears fully matte black and is named black silver. The light absorber includes a hierarchical structure with Ag nanoparticles attached on three-dimensional SiO2 nanostructures, resulting in ultrahigh absorption. Strong localized surface plasmon resonance hybridization together with multiple scattering causes the perfect light absorption. Using the black silver as a light absorber for P-TE power generation, it can achieve a peak voltage density as high as 82.5 V m-2 under a solar intensity of 100 mW cm-2, which is large enough to power numerous electronic devices. By assembling 20 thermoelectric modules in series, we test their possibility of practical application, and they can also achieve an average voltage density of 70.66 V m-2. Our work opens up a promising technology that facilitates high-efficiency and scalable solar energy conversion via the P-TE effect.