Unusual performances of metamaterials such as negative index of refraction, memory effect, and cloaking originate from the resonance features of the metallic composite atom [1][2][3][4][5][6] . Indeed, control of metamaterial properties by changing dielectric environments of thin films below the metallic resonators has been demonstrated [7][8][9][10][11] . However, the dynamic control ranges are still limited to less than a factor of 10, 7-11 with the applicable bandwidth defined by the sharp resonance features. Here, we present ultra-broad-band metamaterial thin film with colossal dynamic control range, fulfilling present day research demands. Hybridized with thin VO 2 (vanadium dioxide) 12-18 films, nanoresonator supercell arrays designed for one decade of spectral width in terahertz frequency region show an unprecedented extinction ratio of over 10000 when the underlying thin film experiences a phase transition. Our nanoresonator approach realizes the full potential of the thin film technology for long wavelength applications.

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impressive progress in their power conversion efficiency (PCE). A PSC is a solar cell with a light harvesting layer composed of an organic/inorganic hybrid compound with a unique crystal structure of perovskite. In the past decade, the efficiency of PSCs has grown rapidly from 3.8% in 2009 to 22.1% [1] and is far superior to the efficiency of conventional thin-film solar cells and comparable to that of single-crystal silicon solar cells. The synergistic combination of ambipolar charge transport properties, long carrier lifetime, and broadband absorption of organic/inorganic lead halide with the perovskite structure, is responsible for the exceptionally high PCE. [2] The low material cost and solution-based processability also makes PSCs economically attractive. For these reasons, PSCs are considered to be a promising candidate for next generation solar cells.Despite the marked progress on device efficiency and fabrication methods, the instability of PSCs critically hampers the commercialization of PSCs. As reported, the lead halide perovskite film is prone to damage upon exposure to water, and most PSC devices with an organic hole-transporting material (HTM) are not stable under thermal stress at high temperature, [3] which must be overcome because solar cells will be installed and operated under a harsh, outdoor environment when used in daily life.In this regard, many research efforts have been made to enhance the intrinsic stability of the perovskite materials against water vapor by tailoring the perovskite materials. Seok and co-workers suggested a series of mixed halide perovskite materials consisting of CH 3 NH 3 PbI 3−x Br x that showed improved environmental stability compared to conventional CH 3 NH 3 PbI 3 (MAPbI 3 ). [4] Recently, Karunadasa and co-workers introduced a hydrophobic bulky cation into a 3D perovskite lattice to produce a 2D layered structure with higher stability. [5] Selective organic layers in PSCs were replaced with inorganic charge transporting materials, such as NiO x and ZnO nanoparticles, [6] for which the inorganic oxide materials also act as an encapsulation layer to prevent water ingress into the device. Many research efforts on improving the intrinsic stability of the perovskite materials against moisture have been attempted, but those approaches are still far from capable of ensuring the long-term stability of the PSC device required for real field operations. The stability of a perovskite solar cell (PSC) is enhanced significantly by applying a customized thin-film encapsulation (TFE). The TFE is composed of a multilayer stack of organic/inorganic layers deposited by initiated chemicalvapor deposition and atomic layer deposition, respectively, whose water vapor transmission rate is on the order of 10 −4 g m −2 d −1 at an accelerated condition of 38 °C and 90% relative humidity (RH). The TFE is optimized, taking into consideration various aspects of thermosensitive PSCs. Lowering the process temperature is one of the most effective methods for minimizing the thermal damage ...

Advances in device technology have been accompanied by the development of new types of materials and device fabrication methods. Considering device design, initiated chemical vapor deposition (iCVD) inspires innovation as a platform technology that extends the application range of a material or device. iCVD serves as a versatile tool for surface modification using functional thin film. The building of polymeric thin films from vapor phase monomers is highly desirable for the surface modification of thermally sensitive substrates. The precise control of thin film thicknesses can be achieved using iCVD, creating a conformal coating on nano-, and microstructured substrates such as membranes and microfluidics. iCVD allows for the deposition of polymer thin films of high chemical functionality, and thus, substrate surfaces can be functionalized directly from the iCVD polymer film or can selectively gain functionality through chemical reactions between functional groups on the substrate and other reactive molecules. These beneficial aspects of iCVD can spur breakthroughs in device fabrication based on the deposition of robust and functional polymer thin films. This review describes significant implications of and recent progress made in iCVD-based technologies in three fields: electronic devices, surface engineering, and biomedical applications.

PurposeTo investigate topographic changes in corneal epithelial thickness (CET) and stromal thickness following orthokeratology (OK) and to determine associated factors affecting refractive changes.MethodsThis study investigated the topographic changes in CET and stromal thickness in 60 myopic eyes that were fitted with OK lenses. CET and stromal thickness were obtained using spectral-domain optical coherence tomography (OCT) before and after OK lens wear. Changes in refractive error and corneal topography data were obtained. The correlation between refractive change and corneal thickness change, and various refractive, lens, and topographic parameters were analyzed using simple regression analysis.ResultsMean refractive error changed by 1.75 ± 0.79 diopters (D). The mean CET of the center zone (2 mm in diameter), paracenter (2 to 5 mm annular ring: 1 to 2.5 mm from center), and mid-periphery (5 to 6 mm annular ring: 2.5 to 3 mm from center) changed by -8.4, -1.4, and +2.7 μm, respectively, after OK lens wear. There was an increase of 2.0, 3.3, and 3.9 μm, respectively, in the center, paracenter, and mid-periphery of the stroma. A larger refractive correction was associated with a flatter base curve of the lens, larger decrease in the central epithelium, and smaller treatment diameter in corneal topography.ConclusionOK lenses caused the central corneal epithelium to thin while the mid-peripheral epithelium and stroma became thicker. Refractive changes during OK are associated with changes in central epithelial thickness, while stromal changes did not contribute significantly.