Small-sized Ag nanoparticle stacked films promoted by sustainedly released surfactants for plasmonic broadband super absorption

Abstract

Large-area, highly absorptive films stacked of uniform Ag nanoparticles (AgNPs) with sub-20 nm size were fabricated by magnetron sputtering at the presence of adhesive tape, during which O-containing compounds were sustainedly released from the adhesive glue that acted as gaseous surfactants to promote the nucleation and simultaneously suppress the coalescence of the AgNPs. Plasmonic absorbers of metal-insulator-metal (MIM) configuration with a gradient-thickness insulator layer were constructed by conformally depositing such small-sized AgNP stacked films (S-AgSFs) on alumina templates with V-shaped nanopores. The broadband optical impedance matching of this novel MIM structure enables broadband light absorption from ultraviolet to near-infrared region, by working together with the large absorption cross-section, strong interparticle plasmon coupling of closely stacking small-sized AgNPs, and the light-trapping effect of the porous template. The average absorbance reaches 96.8 % in the visible region and 86.7 % in the 200–1600 nm range, respectively, showing the great potential of this absorber for applications in antireflection, solar energy harvesting and utilizing, etc. This adhesive-tape-assisted physical vapor deposition approach is simple, cost-effective, and can be applied to various types of substrates, which will enrich the fabrication strategy of metal nanostructures with effectively controlled geometries and optical properties.