Silver nanoplate aggregation based multifunctional black metal absorbers for localization, photothermic harnessing enhancement and omnidirectional light antireflection

Abstract

Plasmonic absorbers with broadband light confinement and high photothermic harnessing efficiency are of current interest in various fields with industrialization prospects, such as solar energy harvesting, photothermic conversion and light antireflection. Here we present simple and cost-effective chemical synthesis and electrophoretic deposition methods for the fabrication of large-scale plasmonic absorber layers constructed by silver nanoplate aggregations (SNPAs) with unique morphology. Using numerical simulation and experiments including surface enhanced Raman scattering (SERS) measurement and in situ monitoring of photothermic water evaporation, we revealed the multiple physical processes including far-field scattering suppression, near-field localized light enhancement and highly efficient light-to-heat conversion when SNPAs are under illumination. Owing to these unique optical effects, the SNPAs exhibited multifunctionality with excellent performances. They exhibited an antireflective efficiency of nearly 100% ranging from 400 nm to 1100 nm which is useful in broadband light antireflection. Meanwhile, highly efficient light trapping and super hydrophilic surface characteristics enable them to exhibit significantly enhanced evaporation velocity acceleration of nearly 7 fold, highly competitive in solar energy induced water purification. They are also competent to serve as highly sensitive SERS substrates with a sensitivity of 10⁻⁸ M for R6G molecule detection owing to their significant near-field light enhancement capacity.