Polymer‐Layer‐Free Alignment for Fast Switching Nematic Liquid Crystals by Multifunctional Nanostructured Substrate

Jung, Woo‐Bin; Jeong, Hyeon Su; Jeon, Hwan‐Jin; Kim, Yun Ho; Hwang, Jeong Yeon; Kim, Jae-Hoon; Jung, Hee‐Tae

doi:10.1002/adma.201502641

Cited by 14 publications

(8 citation statements)

References 33 publications

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“…These high‐resolution line templates provided minimal dead spaces (≈1%), which are considerably less than those of conventional microchannels (≈50%). In addition, the high aspect ratio of the line patterns is advantageous for controlling the anchoring energy . Different metals or semiconductors aside from gold can be used as guiding templates provided that different metals or semiconductors can be deposited onto a substrate.…”

Section: Resultsmentioning

confidence: 99%

Sub‐5 nm Dendrimer Directed Self‐Assembly with Large‐Area Uniform Alignment by Graphoepitaxy

Park

Jung

Kwon

et al. 2019

Adv Funct Materials

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Directed self-assembly (DSA) using soft materials is an important method for producing periodic nanostructures because it is a simple, cost-effective process for fabricating high-resolution patterns. Most of the previously reported DSA methods exploit the self-assembly of block copolymers, which generates a wide range of nanostructures. In this study, cylinders obtained from supramolecular dendrimer films with a high resolution (<5 nm) exhibit planar ordering over a macroscopic area via guiding topographical templates with a high aspect ratio (>10) and high spatial resolution (≈20 nm) of guiding line patterns. Theoretical and experimental studies reveal that this property is related to geometrical anchoring on the meniscus region and physical surface anchoring on the sidewall. Furthermore, this DSA of dendrimer cylinders is demonstrated by the non-regular geometry of the patterned template. The macroscopic planar alignment of the dendrimer nanostructure reveals an extremely small feature size (≈4.7 nm) on the wafer scale (>16 cm 2 ). This study is expected to open avenues for the production of a large family of supramolecular dendrimers with different phases and feature dimensions oriented by the DSA approach.

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Section: Resultsmentioning

confidence: 99%

Sub‐5 nm Dendrimer Directed Self‐Assembly with Large‐Area Uniform Alignment by Graphoepitaxy

Park

Jung

Kwon

et al. 2019

Adv Funct Materials

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“…The target of achieving actual large‐scale devices (centimeter length) is accomplished by incorporating the wrinkling‐assisted grating formation with the bottom‐up physical vapor deposition processes. Oblique angle deposition (OAD) [ 41,42 ] based techniques to obtain two different plasmonic resonances viz the SPP and LSPR modes on a flexible PDMS platform are demonstrated, following a simple fabrication protocol. Starting with the basic diffraction properties of metallic surface‐grating, the contrasting anisotropic diffractive behaviors of metallic strips deposited at the edges of a grating (edge‐grating) are explored.…”

Section: Introductionmentioning

confidence: 99%

Exploring Plasmonic Resonances Toward “Large‐Scale” Flexible Optical Sensors with Deformation Stability

Ghosh

Sarkar

Nebel

et al. 2021

Adv Funct Materials

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The next generation of sensors requires a simple yet compact lab on chip-based precise optical detection mechanism where data interpretation can be achieved with minimum effort. Hereby, cost-efficient strategies of manufacturing both propagating surface plasmon polariton (SPP) and localized surface plasmon resonance (LSPR) sensors on flexible platforms are explored via mechanical instabilities and oblique-angled metal evaporation. Centimeter scaled dielectric grating structures produced by plasma oxidation of pre-stressed polydimethylsiloxane film have comprised the substrates, thus imparting inherent flexibility. Subsequently, both continuous and discontinuous 1D-metallic lattices are obtained via vapor deposition of gold at different angles. The optical isotropy (gold surface-grating) and anisotropy (gold edge-grating) are distinctly observed as a difference between forward and backward diffraction efficiencies, backed by analytical correlation to the observed orders. Supported with electromagnetic modeling, the SPP and LSPR excitations are experimentally characterized under reflectance and transmittance measurements, along with a demonstration of their sensing capabilities. The LSPR supported flexible sensor provides superiority in terms of sensitivity, which is investigated under mechanical deformations to exhibit consistency of the resonant wavelength. Such consistency is strategically unraveled via "finite element method" based approaches, thus providing a new paradigm of cost-efficient, large-scaled flexible sensors.

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“…For PSLC devices, the alignment layer plays a critical role in the LC orientation in the off-state and device operation mechanism. Conventionally polyimide is used as an alignment layer [24,25,26], due to its excellent chemical stability, outstanding mechanical properties, and extraordinary dielectric properties. The preparation of a functional polyimide alignment layer is usually carried out by the dehydration cyclization of the precursor polyamide acid (PAA) by thermal or chemical imidization [27,28,29].…”

Section: Introductionmentioning

confidence: 99%

Polymer Stabilized Liquid Crystal Smart Window with Flexible Substrates Based on Low-Temperature Treatment of Polyamide Acid Technology

et al. 2019

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Polymer stabilized liquid crystal (PSLC) devices can be used as smart privacy windows that switch between transparent and opaque states. The polyimide alignment layer of a PSLC device is usually obtained by the treatment of polyamide acid (PAA) with temperatures over 200 °C. This hinders the fabrication of PSLC devices on flexible substrates, which melt at these high temperatures. In this work, the fabrication of a PSLC alignment layer using a lower temperature that is compatible with most flexible substrates, is demonstrated. It was found that the treatment of PAA at 150 °C could generate the same alignment for liquid crystals. Based on this, a PSLC device was successfully fabricated on a flexible polyethylene terephthalate (PET) substrate, demonstrating excellent electro-optic performances.

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Polymer‐Layer‐Free Alignment for Fast Switching Nematic Liquid Crystals by Multifunctional Nanostructured Substrate

Cited by 14 publications

References 33 publications

Sub‐5 nm Dendrimer Directed Self‐Assembly with Large‐Area Uniform Alignment by Graphoepitaxy

Sub‐5 nm Dendrimer Directed Self‐Assembly with Large‐Area Uniform Alignment by Graphoepitaxy

Exploring Plasmonic Resonances Toward “Large‐Scale” Flexible Optical Sensors with Deformation Stability

Polymer Stabilized Liquid Crystal Smart Window with Flexible Substrates Based on Low-Temperature Treatment of Polyamide Acid Technology

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