Showing papers by "Seung Hee Lee published in 2019"
TL;DR: In this article, a simple and versatile approach towards the fabrication of hierarchical nanoporous manganese nickel selenide (MnxNi1-xSe2) and nanosheets as positive and negative electrodes for flexible charge storage devices to achieve ultra-high energy density was proposed.
141 citations
TL;DR: In this paper, a small amount of conductive and anisotropic functionalized carbon nanotubes (f-CNTs) is doped into conventional OILCs.
Abstract: Nano-size distribution of birefringent liquid crystal droplets embedded in the polymer matrix gives rise to an optically isotropic liquid crystal (OILC) phase and the device utilizing OILC composite opens the possibility of alignment layer-free, flexible liquid crystal displays with fast response time. However, few critical issues such as high operating voltages and feeble light scattering are remained to be overcome before their widespread applications. To rectify the drawbacks, a small amount of conductive and anisotropic functionalized carbon nanotubes (f-CNTs) is doped into conventional OILCs. Consequently, switchable electro-optic properties of the proposed approach reveal that driving voltage is decreased by18.7%, response time becomes fast by 27%, and feeble light leakage is reduced to around 3.8 times, compared to conventional one, which helps the proposed approach to be competitive for display and photonic applications of film type of OILCs.
23 citations
22 citations
TL;DR: In this article, Linearly polarized luminescence (LPL) properties and good processability are critical to the development of advanced optical devices, and a method to fabricate polymer-stabilized thin fil...
Abstract: Organic materials with linearly polarized luminescence (LPL) properties and good processability are critical to the development of advanced optical devices. To fabricate polymer-stabilized thin fil...
18 citations
18 citations
TL;DR: In this article, a droplet array which can function as a microlens array (MLA) is prepared by filling a small amount of polyvinyl chloride (PVC) gel into a polymeric cavity.
17 citations
TL;DR: In this paper, the electrochemical properties such as self-discharge, leakage current and voltage holding tests (VHTs) of reduced graphene oxide (RGO) based solid-state symmetric supercapacitors (SSCs) were reported.
16 citations
TL;DR: In this paper, the authors demonstrate the fabrication of zinc oxide-carbon nanotube (ZnO/CNT) heterostructures with tunable photocatalytic activity via microstructure modulation.
12 citations
TL;DR: In this paper, a host-guest effect between highly ordered smectic reactive mesogen (RM) and dichroic dye was used to fabricate ultra-thin coatable polarizers on a single substrate.
11 citations
TL;DR: The enhanced separation lifetime of the photogenerated electron-hole observed by surface photovoltage and photocurrent measurements of the ZnCTethanol hybrid was attributed to the efficient covalent linking of ZnOC and close contact configuration between the f-CNTs and ZnOethanol NRs.
8 citations
TL;DR: In this paper, the authors studied the nitrogen-doped reduced graphene oxide (Ndoped RGO) as an excellent electrode material in energy storage applications and demonstrated the notable stabilities of ∼95.4% via 10,000 galvanostatic charging-discharging (GCD) cycles and ∼93.2% via 8´h voltage holding tests.
DOI•
25 Feb 2019TL;DR: In this article, a flexible liquid crystal (LC) display with an optically isotropic LC-polymer composite is presented. But the design of the flexible display is difficult because the bending of LC displays easily causes change in thickness of the LC layer and orientation of LCs, resulting in deterioration in a displayed image quality.
Abstract: Application of liquid crystal (LC) materials to a flexible device is challenging because the bending of LC displays easily causes change in thickness of the LC layer and orientation of LCs, resulting in deterioration in a displayed image quality. In this work, we demonstrate a prototype device combining a flexible polymer substrate and an optically isotropic LC-polymer composite in which the device consists of interdigitated in-plane switching electrodes deposited on a flexible colorless polyimide substrate and the composite consisting of nano-sized LC droplets in a polymer matrix. The device can keep good electro-optic characteristics even when it is in a bending state because the LC orientation is not disturbed in both voltage-off and -on states. The proposed device shows a high potential to be applicable for future flexible LC devices.
TL;DR: In this article, highly uniform atomically thick YF3 nanobelts and nanowires are fabricated by using an oleylamine assisted colloidal chemical strategy, which can be readily extended to produce ultrathin structures of other lanthanide fluoride systems.
Abstract: Ultrathin nanomaterials are very significant members of the nanocrystalline material family because of their unique properties of broad significance. In the present study, highly uniform atomically thick YF3 nanobelts and nanowires are fabricated by using an oleylamine assisted colloidal chemical strategy. Reaction monitoring demonstrates that two-dimensional lamellar assemblies of YF3 clusters are vital intermediates in the growth process, which transform to ultrathin nanobelts and nanowires depending on the heating temperature. This approach can be readily extended to produce ultrathin structures of other lanthanide fluoride (ErF3, YbF3, TmF3, NdF3, and LaF3) systems. The polarized upconversion emission of Yb3+/Er3+ co-doped YF3 is demonstrated for a domain of a perfectly aligned assembly of parallel ultrathin nanowires. The polarization degree of green, red and infrared emission peaks are 0.32, 0.28 and 0.50, respectively.
TL;DR: A paper-like diffractive film in which nano-structured liquid crystal droplets are embedded in elastomeric monomer incorporated polymer matrix by polymerization induced phase-separation is demonstrated, exhibiting excellent chemical stability against organic and inorganic solvents.
Abstract: We have demonstrated a paper-like diffractive film in which nano-structured liquid crystal droplets are embedded in elastomeric monomer incorporated polymer matrix by polymerization induced phase-separation. The film with voltage-tunable phase grating exhibits an optically isotropic phase with high transparency and an effective chromatic diffraction for an incident white light with sub-millisecond switching time. In addition, the proposed diffractive film is exhibiting excellent chemical stability against organic and inorganic solvents. In this paper, the diffraction properties of test films depending on incident polarization direction, wavelength, and spatial dispersion are characterized. Easy processing and optically isotropic nature of the film imparts potential applications to flexible electro-optic devices that can be widely implemented in wearable photonics.
TL;DR: In this paper, a homogeneously aligned liquid crystal device was proposed for vehicle displays, in which liquid crystal director does tilt and twist deformation in a confined area by both vertical and fringe-electric fields.
Abstract: Liquid crystal displays (LCDs) for vehicle displays should exhibit a fast response time in wide temperature range and wide-viewing angle in horizontal and downward directions without grey-scale inversion but limited brightness in the upward direction because the display images can be reproduced in the front window glass of a vehicle, affecting driver’s front visibility. Currently, fringe-field switching (FFS) liquid crystal device is widely commercialised for high resolution and wide-viewing-angle LCD; however, it needs to improve response times and limit the display brightness in the upward direction. As a solution, we propose a homogeneously aligned liquid crystal device in which liquid crystal director does tilt as well as twist deformation in a confined area by both vertical- and fringe-electric fields, exhibiting about two times faster decay response time than that of conventional FFS mode with suppressed luminance in the upward direction. The proposed liquid crystal device can be applied to ...
01 Jun 2019
01 Jun 2019
Patent•
24 Jul 2019
TL;DR: In this article, a flexible liquid crystal film using a fiber-based folded transparent electrode is described, which consists of a pair of folded transparent electrodes coated with a silver (Ag) nanowire on a thin film composed of a polymer and a nylon-6 nanofiber.
Abstract: Provided are a flexible liquid crystal film using a fiber-based folded transparent electrode, and a manufacturing method thereof. According to one embodiment of the present invention, the flexible liquid crystal film using the fiber-based folded transparent electrode comprises: a pair of fiber-based folded transparent electrodes coated with a silver (Ag) nanowire on a nanofiber transparent thin film composed of a polymer and a nylon-6 nanofiber; and a dispersed liquid crystal formed by curing between the pair of fiber-based folded transparent electrodes.
Patent•
25 Apr 2019TL;DR: In this article, a fiber-based foldable transparent electrode and a manufacturing method therefor are provided, which comprises the steps of: obtaining a nylon-6 nanofiber transparent thin film by coating a nonwoven fabric with a polymer; and spin coating the nylon- 6 nanofibers transparent thin films with a silver nanowire solution.
Abstract: A fiber-based foldable transparent electrode, and a manufacturing method therefor are provided A method for manufacturing a fiber-based foldable transparent electrode, according to the present embodiment, comprises the steps of: obtaining a nylon-6 nanofiber transparent thin film by coating a nylon-6 nanofiber nonwoven fabric with a polymer; and spin coating the nylon-6 nanofiber transparent thin film with a silver nanowire solution
Patent•
24 Apr 2019TL;DR: In this article, a fiber-based foldable transparent electrode and a method of fabricating the same were presented, where the process of forming a transparent thin film by coating a nylon-6 nanofiber nonwoven fabric with a polymer and spincoating it with a silver nanowire solution was described.
Abstract: Provided are a fiber-based foldable transparent electrode and a method of fabricating the same. According to an embodiment of the present invention, a method of fabricating a fiber-based foldable transparent electrode comprises the steps of: forming a nylon-6 nanofiber transparent thin film by coating a nylon-6 nanofiber nonwoven fabric with a polymer; and spin-coating the nylon-6 nanofiber transparent thin film with a silver nanowire solution.
01 Jun 2019
Patent•
03 Oct 2019TL;DR: In this paper, a flexible liquid crystal film using a fiber-based foldable transparent electrode and a method of fabricating the same are provided, which includes a pair of fiber-bifiber transparent electrodes in which a polymer and a Nylon-6 nanofiber is coated with a silver (Ag) nanowire.
Abstract: A flexible liquid crystal film using a fiber-based foldable transparent electrode and a method of fabricating the same are provided. A flexible liquid crystal film using a fiber-based foldable transparent electrode according to an exemplary embodiment of the present disclosure, the flexible liquid crystal film includes: a pair of fiber-based foldable transparent electrodes in which a nanofiber transparent thin film formed of a polymer and a Nylon-6 nanofiber is coated with a silver (Ag) nanowire; and a dispersed liquid crystal formed by being cured between the pair of fiber-based foldable transparent electrodes.
TL;DR: In this article, a thin layer of single-walled carbon nanotubes (SWCNTs) exhibiting optical anisotropy is prepared by electroactively elongating SWCNT agglomerates.
Abstract: A thin layer of single-walled carbon nanotubes (SWCNTs) exhibiting optical anisotropy is prepared by electroactively elongating SWCNT agglomerates. SWCNTs are doped into a reactive mesogen (RM) solution, and the composite solution is spin-coated on an interdigitated-electrode substrate. The spherical shaped SWCNT agglomerates observed in the solution of thin layers are electroactively elongated and aligned along the direction of the external electric field. After elongating the SWCNT agglomerates, the transparency of RM-SWCNT thin composite layers increases by about 14%. In addition, the elongated SWCNT agglomerates present significant optical anisotropy such that an incident light with a polarization direction parallel and perpendicular to the elongated direction of SWCNTs is absorbed and transmitted, respectively. The electroactively elongating strategy adopted to realize the optical anisotropy of SWCNT agglomerates suggests a new way to fabricate an optically anisotropic SWCNT thin layer.
01 Jun 2019