Jerome K. Hyun 교수

The nanoscale diameter and high aspect ratio of nanowires are the foundation of fascinating structure-property relationships derived from confinement, interface effects, and mechanical degrees of freedom. When heterostructures are formed by high-quality growth of dissimilar materials on or within nanowires, the interactions of the low-dimensional components and their interfaces can give rise to electronic, photonic, magnetic, and thermal characteristics that are superior to those of (or unattain

Structural colors refer to colors produced by the interference of light scattered by judiciously arranged nano- or microscopic structures. In this Forum Article, we discuss the use of Mie resonant scattering in structural colors with dielectric and metal-dielectric hybrid structures to achieve notable figures of merit in pixel size and gamut range. Compared with plasmonic structures, resonant dielectric and hybrid structures are subjected to less loss while providing strong field confinement and

Semiconducting nanowires have been demonstrated as promising light-harvesting units with enhanced absorption compared to bulk films of equivalent volume. However, for small diameter nanowires, the ultrahigh aspect ratio constrains the absorption to be polarization selective by responding primarily to the transverse magnetic (TM) light. While this effect is useful for polarization-sensitive optoelectronic devices, practical light-harvesting applications demand efficient light absorption in both T

The water-based renewable chemical energy cycle has attracted interest due to its role in replacing existing non-renewable resources and alleviating environmental issues. Utilizing the semi-infinite solar energy source is the most appropriate way to sustain such a water-based energy cycle by producing and feeding hydrogen and oxygen. For production, an efficient photoelectrode is required to effectively perform the photoelectrochemical water splitting reaction. For this purpose, appropriately en

Ultrafast and reversible colorimetric responses to humidity changes are observed with disordered, nanoporous titania microspheres, optimized in speed and intensity with a monolayer coverage. The response times, defined by intracrystalline diffusion of water molecules, represent the fastest values for colorimetric humidity sensors.

The effective control of the zeroth order diffraction efficiency in phase gratings is a key technique that enables implementation of high‐performance optical elements. An interesting and unexplored application is in the field of phase mask interference lithography, which uses a conformal grating to generate periodic 3D nanopatterns by the optically formed Talbot image. A good understanding of the influence of phase and diffraction on the Talbot image is necessary for achieving rational design of

Microwave absorption of micron-sized BaTiO₃ particle composites are enhanced up to −26 dB by effective control over ferroelectric domain wall motion mediated by axial oxygen vacancies.

Despite their distinctive chemical properties, lossy metals are generally avoided in the design of structural colors because the optical losses can degrade the color vibrancy. Herein, we demonstrate a strategy that allows lossy metals supporting near-wavelength dielectric gratings to achieve high color vibrancy by benefiting from the optical loss rather than suffering from it. By exciting the grating rotated 45° relative to the incident field, s-polarized (s-pol) and p-polarized (p-pol) light ea

We report UV emission from a ZnO nanorod (NR) highly enhanced by coupling of excitons to cavity-enhanced second harmonic generation (SHG). A Ag cavity concentrates the exciting field into the center of the NR, producing an enhanced second harmonic (SH) response through the nonlinearity of ZnO, that spatially overlaps with an ensemble of excitons. Strong coupling to the excitons at room temperature is achieved when the SH response is spectrally tuned to the exciton transition through the NR diame

Visible-light filters constructed from nanostructured materials typically consist of a metallic grating and rely on the excitation of surface plasmon polaritons (SPPs). In order to operate at full efficiency, the number of grating elements needs to be maximized such that light can couple more efficiently to the SPPs through improved diffraction. Such conditions impose a limitation on the compactness of the filter since a larger number of grating elements represents a larger effective size. For e

Dielectric nanospheres are important components for photonic applications, where interactions between whispering gallery modes (WGMs) can be used to construct photonic band structures. Using the electromagnetic fields generated by relativistic electrons in a monochromated 200 keV scanning transmission electron microscope, we record electron energy loss spectral features reflecting the density of states (DOS) of the electric-type WGMs in SiO2 nanospheres over an energy range extending into the fa

29-Fold luminescence enhancement of upconversion nanoparticle-sensitized perovskite quantum dots was achieved by implementing a metal–insulator–metal configuration and plasmonic coupling.

Abstract The ability to completely absorb an electromagnetic (EM) wave with a material much thinner than the wavelength is a prerequisite for achieving ultracompact, flexible, and lightweight EM devices. Herein, a metamaterial microwave perfect absorber is demonstrated as thin as 1/1250 of the target wavelength by coupling an array of metal patches to inverse cross metal antennas through a dielectric separator and with a reflector placed underneath. Compared to a conventional three‐layer absorbe

Metal electrodeposition and dissolution on a transparent electrode enable dynamic switching between the opaque and transparent states, respectively. To be used as dynamic windows, a fully black state must be achieved while maintaining reversibility. Cu is a top candidate that meets the latter criterion but fails the former, producing its characteristic orange tint. As a result, metal additives are often mixed with Cu ions but at the expense of some degree of reversibility. Here, a truly black st