김경식 교수

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 struc

Abstract Sunlight is one of the Earth's clean and sustainable natural energy resources, and extensive studies are conducted on the conversion of solar energy into electricity using photovoltaic (PV) devices. However, single‐junction PV devices cannot break the theoretical efficiency limit known as the Shockley–Queisser limit that is caused by the sub‐bandgap transmission and heat dissipation losses in semiconductors. Solar thermal conversion approaches may provide an alternative way to exceed th

Self-aggregated alumina nanowire structures have been demonstrated by anodization of aluminum and a subsequent pore breaking process for improving the power conversion efficiency of organic solar cells.

An embedded nanosphere dielectric structure on an a-Si ultrathin film improves weighted absorption from 23.8% to 39.9%. The PMMA embedding layer offers a guided wave mode as well as mechanical robustness, in addition to the resonant whispering gallery modes coupling. Broadband light-trapping enhancements are observed by dielectric surface textured structures of hemispheres, nanocones, nanospheres, or embedded nanospheres.

We present a low-cost and versatile high <italic>Q</italic> colorimetric refractive index sensor based on anodic aluminum oxide (AAO) graded-lattice photonic crystal heterostructure (PCH) template controlled by voltage pulse and electrolyte temperature.

Solar steam generation is a promising solar energy harvesting technology to address the global clean energy and water deficiency cost-effectively. In this work, we present a compact plasmonic nanostructure-nanoparticle composite based on haze/GO-rGO/Au enabling multiple purposes such as broadband solar absorption, solar steam generation, and solar desalination. The graphene oxide-reduced GO (GO-rGO) combination allows broadband optical absorption, and the presence of 5 nm Au nanoparticles create

Sunlight-based desalination is one of the most environment-friendly, low-cost methods for obtaining freshwater on the planet. We implemented a biomimetic three-dimensional (3D) solar evaporator, improved by a solar-induced air-flow updraft. A carbon-coated polyvinyl alcohol (PVA) foam allowed us to achieve perfect absorption of ultrabroadband sunlight and continuously provide water to tall 3D structures. Integrating the convection flower (<i>Amorphophallus titanum</i>) and solar chimney structur

A highly versatile and low-cost large-area refractive index sensor capable of refractometric and colorimetric sensing was developed using a plasmon-coupled hybrid nanotemplate of anodic aluminum oxide with a deposited gold nanosurface.

Broadband light absorbers are essential components for a variety of applications, including energy harvesting and optoelectronic devices. Thus, the development of a versatile absorbing structure that is applicable in various operating environments is required. In this study, a material-versatile ultrabroadband absorber consisting of metal-coated self-aggregated Al₂O₃ nanowire bundles with multiscale funnel structures is fabricated. A high absorptance of ∼0.9 over the AM 1.5

We report here structures, constructed with regular polygonal prisms, that exhibit negative Poisson's ratios. In particular, we show how we can construct such a structure with regular <i>n</i>-gonal prism-shaped unit cells that are again built with regular <i>n</i>-gonal component prisms. First, we show that the only three possible values for <i>n</i> are 3, 4 and 6 and then discuss how we construct the unit cell again with regular <i>n</i>-gonal component prisms. Then, we derive Poisson's ratio

We present a facile method of fabricating SERS substrate by combining solvent-assisted nanoimprint lithography and selective etching of block copolymer.

In this work, a multiscale thin-film membrane of self-aggregated anodized aluminum oxide (AAO) nanowire structure was developed to enhance the efficiency of GaSb photovoltaic (PV) cell using both optical haze and passive radiative-cooling effects in a broad region of the solar spectrum. We controlled, (1) the optical properties of thin-film AAO and (2) the plasmonic-induced perfect absorption/emission by changing packing densities and lengths of AAO nanowires during the anodization and wet etchi