Fabrication of Periodic Arrays of Highly Oriented Plasmonic Heterotrimers via Site-Specific Sequential Colloidal Assembly.

Zha, Huaining; Ye, Shunsheng; Zhang, Yiting; Qiao, Runshi; Zheng, Di; Tao, Jing; Tang, Yutian; Sang, Yutao et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Plasmonic nanoarrays show applications in biosensors, nanolasers, and photodetectors, but precisely organizing and orienting nanoparticle (NP) trimers on substrates remains a grand challenge. Here, we present a self-assembly strategy to arrange metallic NPs with distinct diameters into centimeter-scale arrays of highly oriented linear trimers by modulating the balance between capillary forces and coordination-electrostatic interactions. We achieved an 88% yield of plasmonic trimers with ±10° orientation uniformity across 1 cm<sup>2</sup> substrates by optimizing the ionic strength of the NP solutions. The high uniformity and sub-3-nm interparticle gaps of trimers in arrays enabled the collective polarization-dependent optical responses and high-order plasmonic coupling. Our strategy offers a versatile platform for creating complex nanostructure arrays with heterogeneous assemblies for use in plasmonic devices.