Plasmonic nanostructures with enhanced localized optical fields as well as narrow linewidths have driven advances in numerous applications. However, the active engineering of ultranarrow resonances across the visible regime-and within a single system-has not yet been demonstrated. This paper describes how aluminum nanoparticle arrays embedded in an elastomeric slab may exhibit high-quality resonances with linewidths as narrow as 3 nm at wavelengths not accessible by conventional plasmonic materials. We exploited stretching to improve and tune simultaneously the optical response of as-fabricated nanoparticle arrays by shifting the diffraction mode relative to single-particle dipolar or quadrupolar resonances. This dynamic modulation of particle-particle spacing enabled either dipolar or quadrupolar lattice modes to be selectively accessed and individually optimized. Programmable plasmon modes offer a robust way to achieve real-time tunable materials for plasmon-enhanced molecular sensing and plasmonic nanolasers and opens new possibilities for integrating with flexible electronics.plasmonics | nanoparticles | lattice plasmons | mode engineering | flexible substrates S ingle plasmonic nanoparticles exhibit wide resonant linewidths that can be narrowed by diffractive coupling with neighboring particles (1-3) or nanoscale coupling to metal films (4). The integration of plasmonic nanoparticles on top of elastomeric substrates has enabled tuning of the plasmon modes (5-10), but the resonances remain broad because of radiative damping. Although long-range coupling in periodic arrays can result in extremely narrow resonances (full width at half maximum (FWHM) linewidths <5 nm) (11-13), the design criteria for these lattice plasmon modes are stringent, and the quality of the arrays is fixed at the time of fabrication. Here we report a platform that can selectively access and engineer the quality of distinct, broadband plasmon modes over the entire visible spectrum. Aluminum nanoparticle arrays embedded in an elastomeric slab exhibited high-quality resonances (FWHM: 3-7 nm) at wavelengths not possible for gold or silver and that could be continuously tailored over a large wavelength range (>100 nm). We exploited mechanical stretching to improve and tune simultaneously the optical response of asfabricated arrays by shifting the diffraction mode relative to the single-particle dipolar or quadrupolar resonances. Moreover, dipolar and quadrupolar lattice modes could be individually optimized by stretching along different array directions. The ability to realize programmable plasmon modes from a single system enables tunable substrates for fluorescence enhancement, photocatalysis, biosensing, nanolasers, as well as printed color pixels (14-21).Results Fig. 1 summarizes a platform that can achieve continuously tunable, high-quality lattice plasmon modes based on hexagonal arrays of aluminum nanoparticles embedded in an elastomeric slab. Aluminum nanostructures can support plasmon resonances spanning from the UV to near-IR becau...

All forms of energy follow the law of conservation of energy, by which they can be neither created nor destroyed. Light-to-heat conversion as a traditional yet constantly evolving means of converting light into thermal energy has been of enduring appeal to researchers and the public. With the continuous development of advanced nanotechnologies, a variety of photothermal nanomaterials have been endowed with excellent light harvesting and photothermal conversion capabilities for exploring fascinating and prospective applications. Herein we review the latest progresses on photothermal nanomaterials, with a focus on their underlying mechanisms as powerful light-to-heat converters. We present an extensive catalogue of nanostructured photothermal materials, including metallic/semiconductor structures, carbon materials, organic polymers, and twodimensional materials. The proper material selection and rational structural design for improving the photothermal performance are then discussed. We also provide a representative overview of the latest techniques for probing photothermally generated heat at the nanoscale. We finally review the recent significant developments of photothermal applications and give a brief outlook on the current challenges and future directions of photothermal nanomaterials.

This paper reports how the spectral linewidths of plasmon resonances can be narrowed down to a few nanometers by optimizing the morphology, surface roughness, and crystallinity of metal nanoparticles (NPs) in two-dimensional (2D) lattices. We developed thermal annealing procedures to achieve ultranarrow surface lattice resonances (SLRs) with full-width at half-maxima linewidths as narrow as 4 nm from arrays of Au, Ag, Al, and Cu NPs. Besides annealing, we developed a chemical vapor deposition process to use Cu NPs as catalytic substrates for graphene growth. Graphene-encapsulated Cu NPs showed the narrowest SLR linewidths (2 nm) and were stable for months. These ultranarrow SLR nanocavity modes supported even narrower lasing emission spectra and high nonlinearity in the input–output light–light curves.

This paper describes how a memory-based, sequential wrinkling process can transform flat polystyrene sheets into multiscale, three-dimensional hierarchical textures. Multiple cycles of plasma-mediated skin growth followed by directional strain relief of the substrate resulted in hierarchical architectures with characteristic generational (G) features. Independent control over wrinkle wavelength and wrinkle orientation for each G was achieved by tuning plasma treatment time and strain-relief direction for each cycle. Lotus-type superhydrophobicity was demonstrated on three-dimensional G1-G2-G3 hierarchical wrinkles as well as tunable superhydrophilicity on these same substrates after oxygen plasma. This materials system provides a general approach for nanomanufacturing based on bottom-up sequential wrinkling that will benefit a diverse range of applications and especially those that require large area (>cm(2)), multiscale, three-dimensional patterns.

Conspectus Rationally assembled nanostructures exhibit distinct physical and chemical properties beyond their individual units. Developments in nanofabrication techniques have enabled the patterning of a wide range of nanomaterial designs over macroscale (>in.2) areas. Periodic metal nanostructures show long-range diffractive interactions when the lattice spacing is close to the wavelength of the incident light. The collective coupling between metal nanoparticles in a lattice introduces sharp and intense plasmonic surface lattice resonances, in contrast to the broad localized resonances from single nanoparticles. Plasmonic nanoparticle lattices exhibit strongly enhanced optical fields within the subwavelength vicinity of the nanoparticle unit cells that are 2 orders of magnitude higher than that of individual units. These intense electromagnetic fields can manipulate nanoscale processes such as photocatalysis, optical spectroscopy, nonlinear optics, and light harvesting. This Account focuses on advances in exciton–plasmon coupling and light–matter interactions with plasmonic nanoparticle lattices. First, we introduce the fundamentals of ultrasharp surface lattice resonances; these resonances arise from the coupling of the localized surface plasmons of a nanoparticle to the diffraction mode from the lattice. Second, we discuss how integrating dye molecules with plasmonic nanoparticle lattices can result in an architecture for nanoscale lasing at room temperature. The lasing emission wavelength can be tuned in real time by adjusting the refractive index environment or varying the lattice spacing. Third, we describe how manipulating either the shape of the unit cell or the lattice geometry can control the lasing emission properties. Low-symmetry plasmonic nanoparticle lattices can show polarization-dependent lasing responses, and multiscale plasmonic superlatticesfinite patches of nanoparticles grouped into microscale arrayscan support multiple plasmon resonances for controlled multimodal nanolasing. Fourth, we discuss how the assembly of photoactive emitters on the nanocavity arrays behaves as a hybrid materials system with enhanced exciton–plasmon coupling. Positioning metal–organic framework materials around nanoparticles produces mixed photon modes with strongly enhanced photoluminescence at wavelengths determined by the lattice. Deterministic coupling of quantum emitters in two-dimensional materials to plasmonic lattices leads to preserved single-photon emission and reduced decay lifetimes. Finally, we highlight emerging applications of nanoparticle lattices from compact, fully reconfigurable imaging devices to solid-state emitter structures. Plasmonic nanoparticle lattices are a versatile, scalable platform for tunable flat optics, nontrivial topological photonics, and modified chemical reactivities.