Abstract
AbstractBuilding nanoparticle (NP) superlattices formed in a complex fashion by subsets that can be explored separately presents a promising approach to realize the next generation of superlattices for different applications. Here, by incorporating self‐aligned and geometrically different subsets of Au NPs into one matrix with the assistance of multi‐pore anodic alumina oxide templates, scaled‐up NP superlattices are constructed with programmable multiple plasmonic resonances. The inter‐peak spectral distance is tailored in a broad wavelength range from less than 50 nm up to about 1000 nm through altering not only the size and height of each subset, but also the number and nature of the NP subset. Importantly, a mechanical oscillator model is developed to elucidate the microscopic origin of the spectral programmability and to reproduce the parameter dependence of the multiple plasmonic resonances. A photoelectrochemical cell using Au NP superlattice embedded photoanodes is investigated as a proof‐of‐concept, demonstrating a high photoresponse improvement of about 260% compared to that of bare film reference. In light of the compatibility of this technique with other plasmonic materials and the geometrical tunability, these findings enable systematic optical controlling toward optical devices with multimodal plasmonics.
Highlights
By incorporating self-aligned and geometrically different subsets of Au NPs into one matrix with the assistance of multi-pore anodic alumina oxide templates, scaled-up NP superlattices are constructed with programmable multiple plasmonic resonances
In light of the compatibility of this technique with other plasmonic materials and the geometrical tunability, these findings enable systematic optical controlling toward optical devices with multimodal plasmonics
Scanning electron microscope (SEM) images in Figure 1b show that the resulting cubes and cylinders were symmetrically interlaced according to the spatial configuration of the square A and circular B pores
Summary
The electric field profiles around the cubes and the cylinders are similar to those of the single-set counterparts at the peak wavelengths (Figure S2, Supporting Information), implying that the absorbance peaks at 650 nm and 800 nm may originate predominantly from the plasmonic resonance excited in the cubes and cylinders, respectively. Note that strong electric fields induced by the cubes and cylinders are overlapping within the interstitial spaces at both peak wavelengths, which accounts for the spectral shift of both absorbance peaks after putting cubes and cylinders together as compared with that of the original single sets.[29,30] To explore the polarization dependence of the optical response regarding the Au NP superlattice, a series of simulations were performed by increasing the polarization-angle from 0° to 90° (Figure 1g). Minimal variation with the polarization angle was observed due to the symmetric arrangement of NPs, indicating that Au NP superlattices can serve as polarization-independent dual-mode plasmonic oscillators at normal incidence
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