Controlled growth of islands on plasmonic metal nanoparticles represents a novel strategy in creating unique morphologies that are difficult to achieve by conventional colloidal synthesis processes, where the nanoparticle morphologies are typically determined by the preferential development of certain crystal facets. This work exploits an effective surface-engineering strategy for site-selective island growth of Au on anisotropic Au nanostructures. Selective ligand modification is first employed to direct the site-selective deposition of a thin transition layer of a secondary metal, e.g., Pd, which has a considerable lattice mismatch with Au. The selective deposition of Pd on the original seeds produces a high contrast in the surface strain that guides the subsequent site-selective growth of Au islands. This strategy proves effective in not only inducing the island growth of Au on Au nanostructures but also manipulating the location of grown islands. By taking advantage of the iodide-assisted oxidative ripening process and the surface strain profile on Au nanostructures, we further demonstrate the precise control of the islands’ number, coverage, and wetting degree, allowing fine-tuning of nanoparticles’ optical properties.
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Self‐Aligned Anisotropic Plasmonic Nanostructures
Great opportunities emerge not only in the generation of anisotropic plasmonic nanostructures but also in controlling their orientation relative to incident light. Herein, a stepwise seeded growth method is reported for the synthesis of rod‐shaped plasmon nanostructures which are vertically self‐aligned with respect to the surface of colloidal substrates. Anisotropic growth of metal nanostructure is achieved by depositing metal seeds onto the surface of colloidal substrates and then selectively passivating the seed surface to induce symmetry breaking in the subsequent seed‐mediated growth process. The versatility of this method is demonstrated by producing nanoparticle dimers and linear trimers of Au, Au–Ag, Au–Pd, and Au–Cu2O. Further, this unique method enables the automatic vertical alignment of the resulting plasmonic nanostructures to the surface of the colloidal substrate, thereby making it possible to design magnetic/plasmonic nanocomposites that allow the dynamic tuning of the plasmon excitation by controlling their orientation using an external magnetic field. The controlled anisotropic growth of colloidal plasmonic nanostructures and their dynamic modulation of plasmon excitation further allow them to be conveniently fixed in a thin polymer film with a well‐controlled orientation to display polarization‐dependent patterns that may find important applications in information encryption.
more » « less- Award ID(s):
- 1808788
- NSF-PAR ID:
- 10461119
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 31
- Issue:
- 19
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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