Huang-Ming Philip Chen

Polarized photoluminescence from solid films of nematic and chiral-nematic poly(p-phenylene)s

Thermotropic nematic and chiral-nematic poly(p-phenylene)s were prepared into well-aligned films between fused-silica substrates in which conjugated backbones were uniaxially and helically oriented. With unpolarized photoexcitation at 350 nm, a nematic film produced a degree of linear polarization of 9 near the emission peak at 410 nm with no evidence of excimer formation. With the same photoexcitation of a chiral-nematic film, the degree of circular polarization was found to vary from −1.3 in the 390–430 nm spectral region to between +0.3 and +0.9 beyond the edge of the selective reflection band. The crossover behavior unique to light emission from the selective reflection region remains inexplicable with existing theories on light propagation through periodically structured films.

66.4: Surface Polarity Controlled Horizontal Chevron Defect Free Surface Stabilized Ferroelectric Liquid Crystal Devices

The asymmetrical surface polarity controlled hybrid alignment technique was proposed to suppress the alignment defects of half V-shaped switching FLC materials. When the material was cooled from N* to SmC*, two kinds of layer arrangements were formed with opposite spontaneous polarization directions (Ps). Alignment layers with opposite surface polarity direction were utilized in asymmetrical hybrid cells and produced uni-surface-polarity direction. FLC Ps was only controlled by this surface polarity; therefore, double domains were suppressed into mono-domain. A 2.4” prototype TFT-LCD was presented with defect-free alignment texture. This alignment technique provided promising FLC material with well alignment and fast switching for TFT-LCD application.

18.1: Invited Paper: Eco-Display - An LCD-TV Powered by a Battery?

Color break-up (CBU) is a lethal issue of a high light efficiency field-sequential-color (FSC) LCD. Applying local color-backlight-dimming technology to FSC-LCDs, we demonstrated “Stencil-FSC” methods with a field rate as low as 120Hz to render a high luminance “multi-color” image on the first-field and effectively suppress CBU at the same time. In addition, the color filterless LCD with an intelligent LED backlight and even non-polarized LC cell, optical thruput can increase by a factor of 10, yet with lower material cost/count for an Eco-Display.

P‐102: Hysteresis Suppression of Thin‐Film Transistors with Poly (Vinyl Alcohol) Insulator on Flexible Stainless Steel Substrate

The Hysteresis effects can be suppressed in flexible thin-film transistors with poly (vinyl alcohol) insulator without crosslinking agent. The characteristic of hysteresis was greatly reduced by SiO2 nano-particle in PVA solution. The TFTs were fabricated by using a-IGZO as active layer at room temperature. The TFTs exhibited stable performance with field effect mobility (∼10.81 Vs/cm2), high on/off current ratios (∼106), and low threshold voltage (∼−1V) on planarized stainless steel substrate. The transfer curve which measured from various sweep ranges in two different sweep directions suggested that the hysteresis has been successfully suppressed.

Rib-free Ink-Jet Printing Fabrication on Heterogeneous Surfaces

Rib-free ink-jet printing device fabrication on hetrogeneous surfaces opens a new possibility for greener processes. The integrity of ink droplets was maintained with less than 3° contact angle differences on the heterogeneous surfaces after surface treatment. The breaking of color lines and color mixing were avoided by accelerating solvent evaporation. The inks were greatly conserved without the need for additional lithography process for rib structure.

Splay-to-Bend Transition-Free Reactive Monomer Modified Pi-Cell

A reactive monomer modified Pi-cell (RMM-Pi-cell) comprising a layer of liquid crystal (LC) reactive monomer on one surface was prepared to control the surface pretilt angle. The simulation results suggested that a transition-free Pi-cell can be prepared by asymmetrical cell with one 8 deg pretilt angle and the other surface greater than 47deg when the cell gap was smaller than 4 mum. The nematic reactive monomer layer has a molecular average tilt angle over 80deg which allowed the LC molecules to be arranged in a favored bend state in the asymmetrical cell. The critical voltages cannot be found in all 3-mu m RMM-Pi-cells. The cell retardation data confirmed the initial bend orientation with zero voltage applied. Moreover, the light leakage of dark state was reduced. The contrast ratio of RMM-Pi-cell was improved by a factor of 11 compared with an original Pi-cell without using compensation film.

P‐170: Novel Ferroelectric Glassy Liquid Crystal and Mixtures with Wide SmC* Mesophase

A series of ferroelectric glassy liquid crystals (FGLCs) were synthesized and evaluated for their potentials of fast switching ability less than 1 ms. The latest developed FGLC possesses wide chiral smectic C mesophase over 100 °C. The diluted FGLCs mixtures were also investigated using W206A as host. In particular, the 2% FGLC-1 mixture obtains better alignment with good contrast than R2301 (Clariant, Japan) in the same pre-made 2μm cell (from EHC). In the series of FGLC-3 mixtures, the chiral smectic A phase was completely suppressed within all concentrations. These results provide new promising LC materials for fast switching, color sequential display.

Novel ferroelectric liquid crystals consisting glassy liquid crystal as chiral dopants

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 °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 μm 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.

Photonic applications of glassy liquid crystals

Glassy liquid crystals (GLCs) possessing multi-functionalities, excellent morphological stability, and elevated phase transition temperature have been designed and synthesized for photonic device applications. Recent development has been reported on deterministic synthesis approach for scalable process in preparing GLC materials. The advanced processing eases the material preparation and tailors the material properties accordingly to suit device applications. These applications can be found in: (1) chiral nematic GLCs for circularly polarizers and notch filters, (2) photochromic nematic GLC, which can be photomodulated reflective indices in the solid states, for potential applications in nondestructive rewritable optical data storages and photonic switching, and (3) ferroelectric GLCs for potential fast switching light valves.

Solvent-less Repair Inks for Color Filters

Color filter (CF), one of the key components for liquid crystal display (LCD), is costly to make from repeated lithography processes. The defects may be created during the repeated lithography processes. The recycling defect CF panels are environmental unfriendly and not cost-effective process. CF repairing is an important cost-effective technical process to improve product yield. In this study, a solvent-less repaired ink system was studied. The optimized formulas of red, green, blue, and black inks have passed the quality control, reliability, and life-time tests. The new solvent-free ink system possesses the balance characteristics in liquid fluidic, UV reactivity, and color saturation. The energy has been conserved without high temperature process for removing organic solvent. The new system exhibits the state-ofthe- art fabrication process without unnecessary energy waste. As a result, the solvent-less CF repair inks offer a promising result for contributing to a low carbon process in the near future.