Improving Fast-Charging Performance of Lithium-Ion Batteries through Electrode-Electrolyte Interfacial Engineering.

The solid-electrolyte interphase (SEI) is a key element in anode-electrolyte interactions and ultimately contributes to improving the lifespan and fast-charging capability of lithium-ion batteries. The conventional additive vinyl carbonate (VC) generates spatially dense and rigid poly VC species that may not ensure fast Li transport across the SEI on the anode. Here, a synthetic additive called isosorbide 2,5-dimethanesulfonate (ISDMS) with a polar oxygen-rich motif is reported that can competitively coordinate with Li ions and allow the entrance of PF anions into the core solvation structure.

Strategy to Achieve a Pure Red/Green/Blue-Emitting Upconversion Luminescence for Full-Color Displays.

Multicolor tunable upconversion nanoparticles (UCNPs) have garnered attention owing to their diverse applications such as displays, imaging, and security. Typically, achieving multicolor emission from UCNPs requires complicated core/multishell nanostructures comprising a core with at least five shells. Here, we propose a strategy to achieve bright and orthogonal red (R), green (G), and blue (B) upconversion (UC) luminescence without synthesizing complicated core/quintuple-shell or core/sextuple-shell nanostructures.

Exfoliation Technology for Scalable Ligand-Free Core-Semishell Metal Nanoparticle Films.

Core-shell metallic nanoparticles (NPs) are considered promising materials for their multifunctional properties. However, traditionally synthesized NPs have crucial issues that their ligands interfere with the direct interaction between NPs and neighboring materials, and it is very difficult to form a uniform film without the mixture of a template. In this article, we report an unprecedented exfoliation technology for fabricating a scalable ligand-free core-semishell metal NP film based on the evaporation system through a self-assembled monolayer-assisted surface energy control combined with a deep ultraviolet surface treatment around the core NPs.

Intense Near-Infrared Light-Emitting NaYF:Nd,Yb-Based Nanophosphors for Luminescent Solar Concentrators.

In this study, we synthesized NaYF-based downshifting nanophosphors (DSNPs), and fabricated DSNP-polydimethylsiloxane (PDMS) composites. Nd ions were doped into the core and shell to increase absorbance at 800 nm. Yb ions were co-doped into the core to achieve intense near-infrared (NIR) luminescence.

Elemental-Migration-Assisted Full-Color-Tunable Upconversion Nanoparticles for Video-Rate Three-Dimensional Volumetric Displays.

Herein, we demonstrate video-rate color three-dimensional (3D) volumetric displays using elemental-migration-assisted full-color-tunable upconversion nanoparticles (UCNPs). In the heavily doped NaErF:Tm-based core@multishell UCNPs, erbium migration was observed. By tailoring this migration through adjustment of the intermediate shell thickness between the core and the sensitizer-doped second shell, red-green orthogonal upconversion luminescence (UCL) was achieved.

Environmentally friendly, highly efficient, and large stokes shift-emitting ZnSe:Mn/ZnS core/shell quantum dots for luminescent solar concentrators.

In this study, heavy-metal-free orange light-emitting ZnSe:Mn/ZnS doped-core/shell (d-C/S) quantum dots (QDs) were synthesized using a nucleation doping strategy. To synthesize high quality d-C/S QDs with high photoluminescence (PL) quantum yield (QY), the Mn concentration was optimized. The resulting ZnSe:Mn(5%)/ZnS d-C/S QDs showed a high PL QY of 83.

Biocompatible Yb/Er Co-activated La(WO) Upconversion Nanophosphors for Optical Thermometry, Biofluorescent, and Anticancer Agents.

Non-cytotoxic upconversion nanocrystals are preferred candidates because they offer exceptional advantages for numerous applications, ranging from optical thermometry to bioimaging/biomedical applications. In this report, we demonstrate the luminescence characteristics and practical utility of a multifunctional upconversion nanophosphor based on Yb/Er:La(WO) (LWO) flakes. Strong upconversion green emission was observed from 6-mol % Er-doped LWO nanophosphor flakes excited by a 980 nm laser.

A Super-Boosted Hybrid Plasmonic Upconversion Process for Photodetection at 1550 nm Wavelength.

A super-boosted hybrid plasmonic upconversion (UC) architecture comprising a hierarchical plasmonic upconversion (HPU) film and a polymeric microlens array (MLA) film is proposed for efficient photodetection at a wavelength of 1550 nm. Plasmonic metasurfaces and Au core-satellite nanoassembly (CSNA) films can strongly induce a more effective plasmonic effect by providing numerous hot spots in an intense local electromagnetic field up to wavelengths exceeding 1550 nm. Hence, significant UC emission enhancement is realized via the amplified plasmonic coupling of an HPU film comprising an Au CSNA and UC nanoparticles.

Orthogonal R/G/B Upconversion Luminescence-based Full-Color Tunable Upconversion Nanophosphors for Transparent Displays.

Here, excitation orthogonalized red/green/blue upconversion luminescence (UCL)-based full-color tunable rare-earth (RE) ion-doped upconversion nanophosphors (UCNPs) are reported. The LiREF-based core/sextuple-shell (C/6S) UCNPs are synthesized, and they consist of a blue-emitting core, green-emitting inner shell, and red-emitting outer shell, with inert intermediate and outermost shells. The synthesized C/6S UCNPs emit blue, green, and red light under 980, 800, and 1532 nm, respectively.

Bright Blue, Green, and Red Luminescence from Dye-Sensitized Core@Shell Upconversion Nanophosphors under 800 nm Near-Infrared Light.

In this study, Li-based blue- and green-emitting core@shell (C@S) upconversion nanophosphors (UCNPs) and NaGdF-based red-emitting C@S UCNPs were synthesized, and IR-808 dyes were conjugated with the C@S UCNPs to enhance upconversion (UC) luminescence. The surface of the as-synthesized C@S UCNPs, which was originally capped with oleic acid, was modified with BF to conjugate the IR-808 dye having a carboxyl functional group to the surface of the UCNPs. After the conjugation with IR-808 dyes, absorbance of the UCNPs was significantly increased.

Plasmonic-tape-attached multilayered MoS film for near-infrared photodetection.

Molybdenum disulfide has been intensively studied as a promising material for photodetector applications because of its excellent electrical and optical properties. We report a multilayer MoS film attached with a plasmonic tape for near-infrared (NIR) detection. MoS flakes are chemically exfoliated and transferred onto a polymer substrate, and silver nanoparticles (AgNPs) dewetted thermally on a substrate are transferred onto a Scotch tape.

Large-scale nanoporous metal-coated silica aerogels for high SERS effect improvement.

We investigate the optical properties and surface-enhanced Raman scattering (SERS) characteristics of metal-coated silica aerogels. Silica aerogels were fabricated by easily scalable sol-gel and supercritical drying processes. Metallic nanogaps were formed on the top surface of the nanoporous silica network by controlling the thickness of the metal layer.

High quality chalcogenide-silica hybrid wedge resonator.

Chalcogenide glasses, with high nonlinearity and low loss, have captured research interest as an integrated device platform for near- and mid-infrared nonlinear optical devices. Compared to silicon-based microfabrication technologies, chalcogenide fabrication processes are less mature and a major challenge is obtaining high quality devices. In this paper, we report a hybrid resonator design leveraging a high quality silica resonator to achieve high Q factors with chalcogenide.

Scalable variable-index elasto-optic metamaterials for macroscopic optical components and devices.

Optical metamaterials with an artificial subwavelength structure offer new approaches to implement advanced optical devices. However, some of the biggest challenges associated with the development of metamaterials in the visible spectrum are the high costs and slow production speeds of the nanofabrication processes. Here, we demonstrate a macroscale (>35 mm) transformation-optics wave bender (293 mm) and Luneburg lens (855 mm) in the broadband white-light visible wavelength range using the concept of elasto-optic metamaterials that combines optics and solid mechanics.

Resolution enhancement using plasmonic metamask for wafer-scale photolithography in the far field.

Resolution enhancement in far-field photolithography is demonstrated using a plasmonic metamask in the proximity regime, in which Fresnel diffraction is dominant. The transverse magnetic component of the diffracted wave from the photomask, which reduces the pattern visibility and lowers the resolution, was successfully controlled by coupling with the anti-symmetric mode of the excited surface plasmon. We obtained a consistently finely-patterned photoresist surface at a distance of up to 15 μm from the mask surface for 3-μm-pitch slits because of conserved field visibility when propagating from the near-field to the proximity regime.

Lithography-Free Broadband Ultrathin-Film Absorbers with Gap-Plasmon Resonance for Organic Photovoltaics.

Strategies to confine electromagnetic field within ultrathin film emerge as essential technologies for applications from thin-film solar cells to imaging and sensing devices. We demonstrate a lithography-free, low-cost, large-scale method to realize broadband ultrathi-film metal-dielectric-metal (MDM) absorbers, by exploiting gap-plasmon resonances for strongly confined electromagnetic field. A two-steps method, first organizing Au nanoparticles via thermal dewetting and then transferring the nanoparticles to a spacer-reflector substrate, is used to achieve broader absorption bandwidth by manipulating geometric shapes of the top metallic layer into hemiellipsoids.

Improvement of Light Extraction Efficiency in Flip-Chip Light Emitting Diodes on SiC Substrate via Transparent Haze Films with Morphology-Controlled Collapsed Alumina Nanorods.

We demonstrate GaN-based flip-chip light emitting diodes (FC-LEDs) on SiC substrate achieving high extraction efficiency by simply attaching the optically transparent haze films consisting of collapsed alumina nanorods. Through controlled etching time of alumina nanorods, we obtain four types of films that have different morphologies with different optical transmittance and haze properties. We show that the light output power of the FC-LEDs with film, which has 95.

Flexible thin-film black gold membranes with ultrabroadband plasmonic nanofocusing for efficient solar vapour generation.

Solar steam generation has been achieved by surface plasmon heating with metallic nanoshells or nanoparticles, which have inherently narrow absorption bandwidth. For efficient light-to-heat conversion from a wider solar spectrum, we employ adiabatic plasmonic nanofocusing to attain both polarization-independent ultrabroadband light absorption and high plasmon dissipation loss. Here we demonstrate large area, flexible thin-film black gold membranes, which have multiscale structures of varying metallic nanoscale gaps (0-200 nm) as well as microscale funnel structures.

Broadband light-trapping enhancement in an ultrathin film a-Si absorber using whispering gallery modes and guided wave modes with dielectric surface-textured structures.

An embedded nanosphere dielectric structure on an a-Si ultrathin film improves weighted absorption from 23.8% to 39.9%.

Broadband electromagnetic cloaking with smart metamaterials.

The ability to render objects invisible with a cloak that fits all objects and sizes is a long-standing goal for optical devices. Invisibility devices demonstrated so far typically comprise a rigid structure wrapped around an object to which it is fitted. Here we demonstrate smart metamaterial cloaking, wherein the metamaterial device not only transforms electromagnetic fields to make an object invisible, but also acquires its properties automatically from its own elastic deformation.

Broadband optical antireflection enhancement by integrating antireflective nanoislands with silicon nanoconical-frustum arrays.

Based on conventional colloidal nanosphere lithography, we experimentally demonstrate novel graded-index nanostructures for broadband optical antireflection enhancement including the near-ultraviolet (NUV) region by integrating residual polystyrene antireflective (AR) nanoislands coating arrays with silicon nano-conical-frustum arrays. This is a feasible optimized integration method of two major approaches for antireflective surfaces: quarter-wavelength AR coating and biomimetic moth's eye structure.

Tunable subwavelength focusing with dispersion-engineered metamaterials in the terahertz regime.

We develop a terahertz lens with both subwavelength resolution and tunable far-field focal length by extending the surface plasmon (SP) diffraction theory into spoof SPs of slit-groove-structure terahertz metamaterials. The dispersion properties of terahertz groove structures are engineered in the curved depth profile to produce a directional beaming feature and mimic SPs at the same time. The finite-difference time-domain simulation results confirm that the far-field focal position can be tuned by controlling the curvature of the relative electric field phase distribution profile on the output surface.

Quantitative analysis of mixed hydrofluoric and nitric acids using Raman spectroscopy with partial least squares regression.

Mixed hydrofluoric and nitric acids are widely used as a good etchant for the pickling process of stainless steels. The cost reduction and the procedure optimization in the manufacturing process can be facilitated by optically detecting the concentration of the mixed acids. In this work, we developed a novel method which allows us to obtain the concentrations of hydrofluoric acid (HF) and nitric acid (HNO(3)) mixture samples with high accuracy.

Reliable optical measurement of water vapor in highly scattering environment.

Based on tunable diode laser spectroscopy with direct absorption measurement, we developed a reliable measurement scheme which can precisely detect water vapor concentration independent of the scattering (attenuation) caused by the non-water dust particles inside the observed humidity chamber. The relative water vapor concentration was measured at 2nu(1)+nu(3) water vapor transition band by 938 nm distributed feed-back diode laser at different temperatures using the tunable diode laser spectroscopy technique. These relative water vapor concentrations are converted into the absolute water vapor concentrations and we confirmed that the experimental results at different temperatures are consistently independent of the attenuation.