Designer Metasurfaces via Nanocube Assembly at the Air-Water Interface.

The advent of metasurfaces has revolutionized the design of optical instruments, and recent advancements in fabrication techniques are further accelerating their practical applications. However, conventional top-down fabrication of intricate nanostructures proves to be expensive and time-consuming, posing challenges for large-scale production. Here, we propose a cost-effective bottom-up approach to create nanostructure arrays with arbitrarily complex meta-atoms displaying single nanoparticle lateral resolution over submillimeter areas, minimizing the need for advanced and high-cost nanofabrication equipment.

Pushing the Limits of Capillary Assembly for the Arbitrary Positioning of Sub-50nm Nanocubes in Printable Plasmonic Surfaces.

The fabrication of high quality nanophotonic surfaces for integration in optoelectronic devices remains a challenge because of the complexity and cost of top-down nanofabrication strategies. Combining colloidal synthesis with templated self-assembly emerged as an appealing low-cost solution. However, it still faces several obstacles before integration in devices can become a reality.

Nanoparticle Imprint Lithography: From Nanoscale Metrology to Printable Metallic Grids.

Large scale and low-cost nanopatterning of materials is of tremendous interest for optoelectronic devices. Nanoimprint lithography has emerged in recent years as a nanofabrication strategy that is high-throughput and has a resolution comparable to that of electron-beam lithography (EBL). It is enabled by pattern replication of an EBL master into polydimethylsiloxane (PDMS), that is then used to pattern a resist for further processing, or a sol-gel that could be calcinated into a solid material.

Nanocube Epitaxy for the Realization of Printable Monocrystalline Nanophotonic Surfaces.

Plasmonic nanoparticles of the highest quality can be obtained via colloidal synthesis at low-cost. Despite the strong potential for integration in nanophotonic devices, the geometry of colloidal plasmonic nanoparticles is mostly limited to that of platonic solids. This is in stark contrast to nanostructures obtained by top-down methods that offer unlimited capability for plasmon resonance engineering, but present poor material quality and have doubtful perspectives for scalability.

Monocrystalline Methylammonium Lead Halide Perovskite Materials for Photovoltaics.

Lead halide perovskite solar cells have been gaining more and more interest. In only a decade, huge research efforts from interdisciplinary communities enabled enormous scientific advances that rapidly led to energy conversion efficiency near that of record silicon solar cells, at an unprecedented pace. However, while for most materials the best solar cells were achieved with single crystals (SC), for perovskite the best cells have been so far achieved with polycrystalline (PC) thin films, despite the optoelectronic properties of perovskite SC are undoubtedly superior.

Monocrystalline Nanopatterns Made by Nanocube Assembly and Epitaxy.

Monocrystalline materials are essential for optoelectronic devices such as solar cells, LEDs, lasers, and transistors to reach the highest performance. Advances in synthetic chemistry now allow for high quality monocrystalline nanomaterials to be grown at low temperature in solution for many materials; however, the realization of extended structures with control over the final 3D geometry still remains elusive. Here, a new paradigm is presented, which relies on epitaxy between monocrystalline nanocube building blocks.

Integrating Sphere Microscopy for Direct Absorption Measurements of Single Nanostructures.

Nanoscale materials are promising for optoelectronic devices because their physical dimensions are on the order of the wavelength of light. This leads to a variety of complex optical phenomena that, for instance, enhance absorption and emission. However, quantifying the performance of these nanoscale devices frequently requires measuring absolute absorption at the nanoscale, and remarkably, there is no general method capable of doing so directly.

3D multi-energy deconvolution electron microscopy.

Three-dimensional (3D) characterization of nanomaterials is traditionally performed by either cross-sectional milling with a focused ion beam (FIB), or transmission electron microscope tomography. While these techniques can produce high quality reconstructions, they are destructive, or require thin samples, often suspended on support membranes. Here, we demonstrate a complementary technique allowing non-destructive investigation of the 3D structure of samples on bulk substrates.

AgFeS -Nanowire-Modified BiVO Photoanodes for Photoelectrochemical Water Splitting.

Photoelectrochemical water splitting is a promising and environmentally friendly route for the conversion of solar energy into hydrogen. However, the efficiency of this energy conversion process is low because of the limited light absorption and rapid bulk recombination of charge carriers. In this study, the combination of a novel ternary sensitizer AgFeS , having a narrow bandgap of 0.

Solution-Grown Silver Nanowire Ordered Arrays as Transparent Electrodes.

A transparent conducting film composed of regular networks of silver nanowires is obtained by combining a soft solution process (Tollens' reaction) and nanoimprint lithography. The solution-grown nanowire networks show a threefold higher conductivity than grids obtained by metal evaporation. This is due to the larger grain size in the solution-grown nanowires, which results in a strong reduction of electron scattering by grain boundaries.

Transformation of Ag nanowires into semiconducting AgFeS2 nanowires.

We report on the synthesis of semiconducting AgFeS2 nanowires, obtained from the conversion of Ag nanowires. The study of the conversion process shows that the formation of Ag2S nanowires, as an intermediate step, precedes the conversion into AgFeS2 nanowires. The chemical properties of AgFeS2 nanowires were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy at intermediate steps of the conversion process and show that the temperature at which the reaction takes place is critical to obtaining nanowires as opposed to nanotubes.

Solution-phase epitaxial growth of quasi-monocrystalline cuprous oxide on metal nanowires.

The epitaxial growth of monocrystalline semiconductors on metal nanostructures is interesting from both fundamental and applied perspectives. The realization of nanostructures with excellent interfaces and material properties that also have controlled optical resonances can be very challenging. Here we report the synthesis and characterization of metal-semiconductor core-shell nanowires.

Lanthanide luminescence enhancements in porous silicon resonant microcavities.

In this paper, the covalent immobilization and luminescence enhancement of a europium (Eu(III)) complex in a porous silicon (pSi) layer with a microcavity (pSiMC) structure are demonstrated. The alkyne-pendant arm of the Eu(III) complex was covalently immobilized on the azide-modified surface via ligand-assisted "click" chemistry. The design parameters of the microcavity were optimized to obtain an efficient luminescence-enhancing device.

Dip biosensor based on localized surface plasmon resonance at the tip of an optical fiber.

A dip biosensor is realized by depositing metallic nanoparticles onto the tip of a cleaved optical fiber. Light coupled into the fiber interacts with the localized surface plasmons within the nanoparticles at the tip; a portion of the scattered light recouples into the optical fiber and is analyzed by a spectrometer. Characterization of the sensor demonstrates an inverse relationship between the sensitivity and the number of particles deposited onto the surface, with smaller quantities leading to greater sensitivity.

Radiative-surface plasmon resonance for the detection of apolipoprotein E in medical diagnostics applications.

Unlabelled: Surface plasmon resonance (SPR)-based sensors enable the rapid, label-free and highly sensitive detection of a large range of biomolecules. We have previously shown that, using silver-coated optical fibers with a high surface roughness, re-scattering of light from the surface plasmons is possible, turning SPR into a radiative process. The efficacy of this platform has proven for the detection of large biomolecules such as viruses, proteins and enzymes.

Switching of fluorescence mediated by a peroxynitrite-glutathione redox reaction in a porous silicon nanoreactor.

A nanostructured porous silicon chip functionalized with dichlorofluorescein is employed as a nanoreactor to respond to Reactive Oxygen Species (ROS) and to real-time studying redox reactions.

Bioconjugate functionalization of thermally carbonized porous silicon using a radical coupling reaction.

The high stability of Salonen's thermally carbonized porous silicon (TCPSi) has attracted attention for environmental and biochemical sensing applications, where corrosion-induced zero point drift of porous silicon-based sensor elements has historically been a significant problem. Prepared by the high temperature reaction of porous silicon with acetylene gas, the stability of this silicon carbide-like material also poses a challenge--many sensor applications require a functionalized surface, and the low reactivity of TCPSi has limited the ability to chemically modify its surface. This work presents a simple reaction to modify the surface of TCPSi with an alkyl carboxylate.

Fast optical vapour sensing by Bloch surface waves on porous silicon membranes.

The coupling of optical Bloch surface waves at the truncated end of one dimensional porous silicon photonic crystals is exploited for fast vapour sensing. Self-standing multilayered membranes bound to transparent substrates were fabricated by electrochemical etching and used in an attenuated total reflection configuration to resonantly excite the surface waves and perform real-time sensing.