Browsing by Author "Chen, Huang-Ming Philip"

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Anchoring Energy Enhancement for Plasma Alignment Technology
(2009)
Hsu, Chih-Yi
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Lee, Tse-Hsien
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Chen, Huang-Ming Philip
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Kuo, Hui-Chien J.
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Chen, Yi-Fan
The oxygen plasma post-treatment was adopted for alignment preparation in Ar plasma alignment process. The light leakage at the dark slate was suppressed by the new treatment. The NEXAFS data suggested that the out of plane carbonyl groups have been regenerated under oxygen plasma post-treatment. The polar anchoring energy was two times increased comparing to the Ar treated PI. The cell's EO properties by new plasma treatment were comparable to the rubbed PI surface.
Anisotropic exciton relaxation in nanostructured metal (Zn and F16Zn)-phthalocyanine
(2015-02-09)
Ahn, Hyeyoung
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Liou, Wei-Hyun
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Chen, Huang-Ming Philip
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Hsu, Chia-Hung
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光電工程學系
We report ultrafast excited state dynamics of zinc phthalocyanine and zinc hexadecafluoro phthalocyanine thin films which have nanorod-like structures. Excitons in the singlet states undergo multi-exponential relaxation processes to the ground state and the singlet lifetime within a few tens of picoseconds is attributed to the diffusion-limited exciton annihilation process. Diffusive migration of the singlet excitons shows the anisotropic lifetimes depending on the polarization of probe beam. Similar anisotropy is observed in the X-ray diffraction data which exhibits long-range alignment of molecular columns along the long axis of nanorod, whereas disordered arrangement in lateral direction to the axis of nanorod. (C) 2015 Optical Society of America
Characterization of the spatially anamorphic phenomenon and temporal fluctuations in high-speed, ultra-high pixels-per-inch liquid crystal on silicon phase modulator
(2019-10-28)
Yang, Jhou-Pu
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Wu, Feng-Ping
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Wang, Pei-Sin
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Chen, Huang-Ming Philip
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光電工程學系
High-birefringence liquid crystal (LC) in ultrathin LCOS panels was adopted to prepare high phase precision (mSTD =lambda/50) and phase accuracy (mAPAE%similar to 8%) with suppressed pixel-level crosstalk effects. In conjunction with optimized digital driving scheme, the zero order light loss was found directly related to the phase accuracy error. Meanwhile, the world's fastest pure phase modulation LCOS with a response time of similar to 0.87 ms at 45 degrees C was also achieved. The low-temporal flicker (P-P similar to 2.0%) with high-speed LC responses was demonstrated by applying new digital driving scheme. Finally, the 4K2 K LCOS-SLM (similar to 7000 PPI) was evaluated its difficulties and opportunities. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Critical voltage reduction by alignment layer modification in Pi-cells
(2007)
Wu, Wei-Ching
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Chen, Yi-Fan
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Chen, Szu-Fen
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Chen, Huang-Ming Philip
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光電工程學系
A new approach which can effectively lower the critical voltage (Vcr) of pi cell has been realized in this study. New structure of pi r cell can increase the control range of driving voltage, which makes the gray scale manipulation near Vcr more stable without loosing the fast response property.
Defect-free half-V-mode ferroelectric liquid-crystal device
(2010-11-01)
Lin, Chi-Wen
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Chen, Huang-Ming Philip
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光電工程學系
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Department of Photonics
The horizontal chevron defect found in a half-V-mode ferroelectric-liquid-crystal (HV-FLC) device can be suppressed by lowering the FLC's total free energy. The energy levels between spontaneous polarization (P(S)) up and down domains were degenerated by asymmetrical-alignment treatments. The difference in the polar surface coefficient (gamma(2)) was the key to suppressing the alignment defect. Alignment layers with opposite surface polarities and different anchoring energies were applied to control the sign and value of gamma(2). The asymmetric cells of PI(rub) - PI(plasma) (rubbed polyimide and plasma-treated polyimide surfaces), PVA(rub) - PI(plasma) (rubbed polyvinyl alcohol and plasma-treated polyimide surfaces), and PVA(rub) - PI(rub) (both rubbed PI and PVA) alignment conditions presented defect-free alignment textures under a slow-cooling process. Among these different alignment treatments, the PVA(rub) - PI(rub) treated cell demonstrated the best alignment result, benefited by the largest difference in polar surface coefficient.
Defect-free half-V-mode ferroelectric liquid-crystal device
(2010-11-01)
Lin, Chi-Wen
;
Chen, Huang-Ming Philip
;
顯示科技研究所
;
Institute of Display
The horizontal chevron defect found in a half-V-mode ferroelectric-liquid-crystal (HV-FLC) device can be suppressed by lowering the FLC's total free energy. The energy levels between spontaneous polarization (P-S) up and down domains were degenerated by asymmetrical-alignment treatments. The difference in the polar surface coefficient (gamma(2)) was the key to suppressing the alignment defect. Alignment layers with opposite surface polarities and different anchoring energies were applied to control the sign and value of gamma(2). The asymmetric cells of PIrub - PIplasma (rubbed polyimide and plasma-treated polyimide surfaces), PVA(rub) - PIplasma (rubbed polyvinyl alcohol and plasma-treated polyimide surfaces), and PVA(rub) - PIrub (both rubbed PI and PVA) alignment conditions presented defect-free alignment textures under a slow-cooling process. Among these different alignment treatments, the PVA(rub) - PIrub treated cell demonstrated the best alignment result, benefited by the largest difference in polar surface coefficient.
Efficient p-i-n Top-emitting Flexible Organic Light Emitting Diodes on Planarized Stainless Steel Foil
(2009)
Su, Shang-Yu
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Ho, Meng-Huan
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Kao, Pei-Yi
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Wu, Chang-Yen
;
Peng, Yi-Hao
A high-efficiency p-i-n top-emitting flexible organic light emitting diode (TFOLED) employing highly reflective Ag as anode and semitransparent Ca/Ag as cathode was fabricated on SS substrate which was insulated and planarized with a specially formulated photoresist coating. By incorporating p-dopant (WO(3)) and a new n-dopant (PAK2) in hole and electron transparent layers, respectively, along with an optimized microcavity structure, a green fluorescent C545T doped Alq(3) TOLED on SS substrate achieved one of the highest efficiencies of 26.7 cd/A and 19.8 lm/W at 20 mA/cm(2) reported for flexible OLEDs.
Electrooptical properties and surface treatment for FLCS using ferroelectric glassy liquid crystals as chiral pants
(2007)
Huang, Yao-Ching
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Chen, Huang-Ming Philip
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顯示科技研究所
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Institute of Display
Surface alignment for FLCs was one of largest issue for real application in display. In this study, two novel FGLC materials were used as chiral dopants and evaluated their electrooptical properties. To suppressed defects and multi-domains occurring in traditionally polyimide-coated cells, hybrid cells coated with poly vinyl alcohol (PVA) and polyimide(PI) were used to improve the alignment issue. As a result, better alignment, larger mono-domain area were achieved in hybrid cells than pre-made cells, which providing a potential application in flat panel displays.
Evaluation of Kerr constant of blue-phase liquid crystals by measuring off-axis retardation in vertical electric field cells
(2011-09-20)
Hsieh, Pao-Ju
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Chen, Huang-Ming Philip
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光電工程學系
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Department of Photonics
Because of the nonuniform electric field of the in-plane-switching cell in the thickness direction, an accurate and efficient way for evaluating the Kerr constant of blue-phase liquid crystal (BPLC) needs to be developed. This study demonstrates a method for evaluating the Kerr constant by measuring the off-axis-induced retardation (R(th)) change in normal vertical field cells using a commercial polarimeter. The angle-dependent behavior of the R(th) change is observed as an electric-tunable positive C retarder. In this paper, a sigmoid fitting model has been chosen for calculating the Kerr constant for considering the very small intrinsic birefringence of the BPLC. (C) 2011 Optical Society of America
Excellent Color Quality of White-Light-Emitting Diodes by Embedding Quantum Dots in Polymers Material
(2016-01-01)
Lin, Huang-Yu
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Wang, Sheng-Wen
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Lin, Chien-Chung
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Chen, Kuo-Ju
;
Han, Hau-Vei
This study employs the polyfluorene composite (called Green B) with several colors of quantum dots to generate the high-color-rendering index (CRI) white LEDs. The Green B polymer is a good candidate to manufacture the hybrid w-LED because of its good quantum efficacy. The hybrid w-LEDs are fabricated by the mixing of Green B with yellow quantum dots and red quantum dots or orange quantum dots to obtain the correlated color temperatures of 3500 and 5500 K. The use of the hybrid polymer/QDs w-LEDs is proved to be beneficial as QD w-LEDs can improve the CRI up to 90 in 3500 K. The luminous efficiency of such devices can be as high as 17.2l m/W.
Ferroelectric LC Binary Phase Grating Based on Striped Electrodes
(2011)
Lin, Chi-Wen
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Chen, Huang-Ming Philip
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交大名義發表
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光電工程學系
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National Chiao Tung University
Using the asymmetric alignment technique, based on double-side striped electrodes, the electrically tunable ferroelectric LC grating, approaching calculated diffraction efficiency is demonstrated. The width of thin striped electrodes is designed smaller than half of the grating pitch to compensate for the fringe field effect and thus improve the diffraction efficiency.
Gas Sensing Ability on Polycrystalline-Silicon Nanowire
(2018-01-01)
Lo, Yen-Ren
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Chen, Huang-Ming Philip
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Yang, Yuh-Shyong
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Lu, Ming-Pei
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生物科技學系
Trace of protic gases can alter the conductivity of the polycrystalline silicon nanowire (poly-Si NW) field effect transistor (FET). The aprotic gases have no effect on the electrical parameters. The proposed mechanism is due to the surface grain boundary of poly-Si NW. The direct evidence is obtained from the comparison between single-and poly-Si NW. The electrical parameters are varied according to the relative humidity levels. Nevertheless, the water molecules can be removed by vacuum indicating that it is physical absorption on the surface. As a result, the poly-Si NW FET has potential to be a reusable device for protic gas sensor. (C) The Author(s) 2018. Published by ECS.
Gray-scale, low color shift cholesteric liquid crystal displays
(2007)
Wu, Keng-Jui
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Hsieh, Pao-Ju
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Chen, Huang-Ming Philip
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光電工程學系
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Department of Photonics
Cholesteric Liquid Crystals (CLCs) have severe blue shift when applied voltage. Lack of gray scale also hinders their display application. In this study, the value of CLC hosts' dielectric anisotropic (Delta epsilon) was varied by mixing negative and positive nematic LCs. Based on this method, the color shift (Delta E*ab) was greatly improved from 49.89 to 10.80.
Hysteresis-free polymer-stabilised blue phase liquid crystals comprising low surface tension monomers
(2015-02-01)
Hsieh, Pao-Ju
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Chen, Huang-Ming Philip
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分子醫學與生物工程研究所
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光電工程學系
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顯示科技研究所
Partial replacement of fluoroacrylates in the monomer composition is able to reduce the free energy of polymer-stabilised blue phase liquid crystal (PSBPLC) due to their low surface tension. The ease of blue phase platelet texture formation is observed under fast cooling and short annealing time before ultraviolet irradiation. The peak driving voltages are dramatically decreased from 9% to 16% in the resulting PSBPLCs. In addition, the hysteresis is completely suppressed in the PSBPLC containing 3FM-M1. The other PSBPLC containing fluoroacrylates retain very small hysteresis (oV<0.8V) regardless the fluorine atom numbers. In comparison with current PSBPLCs, the fluoroacrylates serve as mesophase enhancer not only to promote the blue phase formation but also to improve the electro-optical properties.
Low driving voltage with clean aligned ferroelectric liquid crystal devices
(2007)
Lin, Chi-Wen
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Li, Kun-Zhan
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Yang, Chin-Wei
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Chen, Huang-Ming Philip
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顯示科技研究所
Low driving voltage FLC material, R3206 with Vsat. at 3.5V (AZ Electronic Materials), and its mixtures were under evaluation for potential TFT display application. Poor alignment issue was overcome by the diluted pitch mixtures and asymmetric hybrid alignment cells. In the series of diluted pitch mixtures, the contrast and alignment are better than pure compound in pre-made cells (1.8 +/- 0.1 mu m, from EHC). In particular, the 70% R3206 mixture showed the best result with low driving voltage helow 5V and fast response time (T (on) + T (off)) under 1.1 ms. The hybrid alignment cell was successfully suppressed horizontal chevron defects and achieved the best contrast ratio of 750. These results provide promising FLC Materials with low driving voltage, well aligned, and fast switching for TFT-LCD application.
Medical displays by using plasma-beam-alignment technology
(2008-01-01)
Lee, Chin-Yang
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Liu, Chi-Hung
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Chen, Chih-Wei
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Miki, Saodo
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Chen, Huang-Ming Philip
Novel anode layer plasma within minimum chamber space was developed for non-contact alignment process. The plasma-treated polyimide (PI) surface showed no particle contamination and no micro-scratches. Surface morphology was investigated by using scanning electron microscope (SEM), an atomic force microscope (AFM), and X-ray photoemission spectroscopy. The different oxygen-to-carbon ratio ([O]/[C] ratio) for XPS spectra indicated a composition change after plasma treatment. Surface pretilt angles were varied from 0 to 2.1 degrees under different plasma exposure times. Finally, a prototype 20.8-in. QXGA IPS-mode gray-scale medical liquid-crystal display was successfully demonstrated with high contrast ratio, excellent uniformity, and wide viewing angle using this new plasma-beam-alignment technique.
Novel ferroelectric liquid crystals consisting glassy liquid crystal as chiral dopants
(2006-01-01)
Chen, Huang-Ming Philip
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Tsai, Yun-Yen
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Lin, Chi-Wen
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Shieh, Han-Ping David
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光電工程學系
A series of ferroelectric liquid crystals consisting new glassy liquid crystals (GLCs) as chiral dopants were prepared and evaluated for their potentials in fast switching ability less than 1 ms. The properties of pure ferroelectric glassy liquid crystals (FGLCs) and mixtures were reported in this paper. In particular, the novel FGLC possessing wide chiral smectic C mesophase over 100 degrees C is able to suppress smectic A phase of host. The mixture containing 2.0 % GLC-1 performs greater alignment ability and higher contrast ratio than R2301 (Clariant, Japan) in a 2 mu m pre-made cell (EHC, Japan). These results indicate that novel FLC mixtures consisting glassy liquid crystals present a promising liquid crystal materials for fast switching field sequential color displays.
Novel ferroelectric liquid crystals consisting glassy liquid crystal as chiral dopants - art. no. 63320G
(2006)
Chen, Huang-Ming Philip
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Tsai, Yun-Yen
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Lin, Chi-Wen
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Shieh, Han-Ping David
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光電工程學系
A series of ferroelectric liquid crystals consisting new glassy liquid crystals (GLCs) as chiral dopants were prepared and evaluated for their potentials in fast switching ability less than 1 ms. The properties of pure ferroelectric glassy liquid crystals (FGLCs) and mixtures were reported in this paper. In particular, the novel FGLC possessing wide chiral smectic C mesophase over 100 degrees C is able to suppress smectic A phase of host. The mixture containing 2.0 % GLC-1 performs greater alignment ability and higher contrast ratio than R2301 (Clariant, Japan) in a 2 mu m pre-made cell (EHC, Japan). These results indicate that novel FLC mixtures consisting glassy liquid crystals present a promising liquid crystal materials for fast switching field sequential color displays.
Optical cross-talk reduction in a quantum-dot-based full-color micro-light-emitting-diode display by a lithographic-fabricated photoresist mold
(2017-10-01)
Lin, Huang-Yu
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Sher, Chin-Wei
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Hsieh, Dan-Hua
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Chen, Xin-Yin
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Chen, Huang-Ming Philip
In this study, a full-color emission red-green-blue (RGB) quantum-dot (QD)-based micro-light-emitting-diode (micro-LED) array with the reduced optical cross-talk effect by a photoresist mold has been demonstrated. The UV micro-LED array is used as an efficient excitation source for the QDs. The aerosol jet technique provides a narrow linewidth on the micrometer scale for a precise jet of QDs on the micro-LEDs. To reduce the optical cross-talk effect, a simple lithography method and photoresist are used to fabricate the mold, which consists of a window for QD jetting and a blocking wall for cross-talk reduction. The cross-talk effect of the well-confined QDs in the window is confirmed by a fluorescence microscope, which shows clear separation between QD pixels. A distributed Bragg reflector is covered on the micro-LED array and the QDs' jetted mold to further increase the reuse of UV light. The enhanced light emission of the QDs is 5%, 32%, and 23% for blue, green, and red QDs, respectively. (C) 2017 Chinese Laser Press
Optimization of nano-honeycomb structures for flexible w-LEDs
(2017-08-21)
Lin, Huang-Yu
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Pai, Yung-Min
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Shi, Jing-xing
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Chen, Xin-Yin
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Lin, Chung-Hsiang
This study presents the low cost fabrication of flexible white-light-emitting diodes (w-LEDs) with nano-honeycomb-structured phosphor films. Extending the dimensions of the nano-honeycomb structures improved the color uniformity of the flexible samples, and the 950-nm pattern sample demonstrated optimal color uniformity because this nano-pattern exhibited an excellent diffusion ability owing to its pitch size. In addition to color uniformity, the use of this nano-pattern improved the luminous efficiency. The 750-nm pattern exhibited the highest luminous efficiency (235.8 lm/W), which was approximately 7% higher than that exhibited by a non-patterned phosphor film sample. Thus, flexible w-LEDs with nano-honeycomb structure optimization have great potential to be used as next-generation lighting sources. (C) 2017 Optical Society of America