LAUSR

(1 of 6) 1600971 Next-generation photonic devices require the concentration of electromagnetic energy to subwavelength scales.[1] Gold and silver nanoparticles (NPs) could be ideal candidates for this purpose, due to their ability to support localized surface plasmons (LSPs).[2] Because of large dephasing, mostly due to nonradiative interand intraband excitations, LSPs have broad spectral linewidths.[3] This implies short plasmon lifetimes limiting the extensive use of isolated gold and silver NPs in applications like plasmonic nanolasers[4] and waveguides.[5] Nanostructures that support low loss plasmons are in the focus of intense research in recent years.[6] While addressing the challenge of narrow linewidths on the single particle level requires the optimization of size, shape, and material composition of NPs, a promising concept capitalizing on rather simple building blocks is the arrangement of NPs into periodic arrays. These arrays were found to show narrow surface lattice resonances (SLRs) as result of coupling between LSPs and diffractive modes.[7] So far, plasmonic arrays supporting SLRs have been fabricated exclusively using lithographic approaches such as electron-beam lithography[7b] and soft interference lithography.[8] However, simple and low-cost fabrication methods suitable for large scale applications that create intense electromagnetic fields with dynamic tunability are yet to be developed.[9] By exchange of the surrounding solvent some tuning of the SLRs has been demonstrated.[4b,9] Here, we address a method suitable for fabricating large area devices that support fully reversible, dynamic actuation of SLR modes. We use an array fabrication employing a combination of wet-chemically synthesized hybrid nanoparticles (NPs) and bottom-up self-assembly. cm2-scale hexagonally ordered arrays of silver nanocrystals (NCs) are manufactured. Applying a polymer top layer yields a smart hybrid device supporting pronounced, spectrally narrow SLRs that can be dynamically and fully reversibly modulated. The synergistic interplay between the plasmonic NC array and the responsive polymer layer yields a smart, temperature-controllable optical gate. Figure 1 illustrates the device preparation based on colloidal self-assembly of silver@gold-poly-N-isopropylacrylamide (Ag@Au-PNIPAM) core–shell NPs (a). The NPs have spherical Reversible Tuning of Visible Wavelength Surface Lattice Resonances in Self-Assembled Hybrid Monolayers