Search

We proposed a new Liquid Crystal (LC) mode named as chiral hybrid in-plane switching (CH-IPS) LC mode for LCD application. However, when LC is injected into a CH-IPS sample, the domains by reverse twist are induced usually. In order to remove such a defect, we investigate what the major factors which have influence on the creation of defects by the reverse twist domain are. By experiment, we define the major factors which have large influence on the formation of domains. By controlling these major factors properly, we can remove defect domains perfectly. [ABSTRACT FROM AUTHOR]

We propose a new structure of a viewing angle controllable liquid crystal display (LCD) consisting of a conventional liquid crystal display (LCD) panel and a thermally variable retardation layer (TVRL) established by uniformly aligned LC cell with transparent indium-tin-oxide electrodes for Joule heating. In the TVRL, nematic phase is transitioned into the isotropic one by Joule heating. From numerical simulations, the intrinsic wide viewing angle was achieved at the isotropic phase of the TVRL by Joule heating, while the narrow viewing angle was obtained at the nematic phase of the TVRL. The structure of the viewing angle control proposed here is adoptable to all LCD modes with the wide viewing angle characteristics. [ABSTRACT FROM AUTHOR]

The electrical characteristics of organic thin film transistors (OTFTs) with self-assembled monolayer (SAM) on the poly(4-vinylphenol) gate insulator have been investigated. The SAM was formed in gas-phase using the atomic layer deposition method onto gate insulator. It is observed that SAM modifies the surface polarity of gate insulator and influence the growth of the subsequent pentacene layer. Improvements of the crystallinity and directionality of pentacene molecules are confirmed by X-ray diffraction measurement. Also, the roughness of the pentacene thin film and the device performance are improved. [ABSTRACT FROM AUTHOR]

Poly[9,9-bis(4'-n-octyloxyphenyl)fluorene-2,7-diyl] (PBOPF), and their random copolymers with alkylphenothiazine [poly(BOPF-co-PTZ)], were synthesized through Ni(0) mediated polymerization. Light-emitting devices were fabricated using these polymers in an ITO (indium tin oxide)/PEDOT:PSS/polymer/Ca/Al configuration. Each EL device constructed with a poly(BOPF-co-PTZ) copolymer exhibited significantly enhanced efficiency and brightness compared to devices constructed from the PBOPF homopolymer. The EL device constructed with poly(84BOPF-co-16PTZ) exhibited the highest luminous efficiency and brightness (8,600 cd/m2 and 2.83 cd/A respectively). [ABSTRACT FROM AUTHOR]

A single substrate flexible display was fabricated by laminating a thin cover film of UV curable photo-polymer on the plastic bottom substrate. The micro-walls of photoresist on the bottom substrate are tightly bound with the cover film to provide the solid mechanical support for preserving the molecular alignment of liquid crystals (LCs). The ability of aligning LCs is induced by rubbed alignment layer on the bottom substrate and micro-grooves formed on the photo-polymer film. We demonstrated a twisted nematic LC mode on the plastic substrate with in-plane switching electrode. The fabrication process and electro-optical characteristic of the device are described. [ABSTRACT FROM AUTHOR]

We investigated the effect of surface wetting on the 2-dimensional anisotropic phase separation. The surface conditions were spatially modulated by laminating several types of alignment materials on the ITO substrate in a periodic square pattern using micro-contact printing methods. 2-dimensional phase separation was obtained without/with UV irradiation and the relative wettability of LC and polymer on alignment layer and ITO surface determined the diffusion direction of each material during phase separation. Furthermore the polymerized wall structures are different for different LC monomer mixing ratio. This technology can be applied to flexible liquid displays. [ABSTRACT FROM AUTHOR]

We investigated interfacial roughness effect of pentacene-based organic thin film transistors on an anisotropic insulator fabricated by obliquely evaporated silicon dioxide. It was observed that the obliquely evaporated gate dielectric layer affected molecular ordering of evaporated pentacene molecules. As the evaporation angle of SiO2 increased, the anisotropic interaction at the dielectric interface and the ordering of organic semiconductor molecules increased. We obtained the anisotropic ratio of the field-effect mobility for carriers transported parallel and perpendicular to the evaporation direction was 2.9. [ABSTRACT FROM AUTHOR]

Electrically switchable microlens array is demonstrated using a stacking system of UV curable polymer, liquid crystalline polymer (LCP) and liquid crystal (LC) layers. The birefringent LCP provides the incident beam focusing ability of polymer microlens structure as well as the LC aligning property. By engaging external voltage to the device, we can obtain fine dynamic characteristics of the focus switching from the polarization tuning ability of twisted nematic LC layer on the flat boundary condition and the light focusing role of polymer microlens structure, separately. The measured focal characteristics are well matched to the calculated ones and arrayed focused spots are easily switched by applying external voltage. This active microlens array is expected to play a critical role in the various photonic systems such as optical switches, beam modulators and 3-D imaging units. [ABSTRACT FROM AUTHOR]

We studied various dynamic characteristics of the transflective liquid crystal display (LCD) having a single cell gap and a single liquid crystal (LC) mode simultaneously. In this configuration, intrinsic optical path difference between transmissive and reflective part was compensated by modifying LC's optic axis with different patterned electrode configurations and voltage application. The angle of electrode was designed to induce appropriate optical retardations in each part and the resultant electro-optic characteristics were matched identically. Also, we minimized the mismatches in grey level by optimizing the angle of reflective part through the simulation. Moreover, the wide viewing characteristics of transflective LCD was verified from the 8-domain LC structure of our sample while only 4-domains can be achieved in the conventional case. By using this technique, we can easily achieve transflective LCD of good performances under same optical setup such as polarizers and retardation films over the whole panel area without complicated fabrication. [ABSTRACT FROM AUTHOR]

We proposed a soft-lithographic technique for patterning liquid crystal (LC) alignment layers. It was demonstrated that a thermoplastic polystyrene layer was patterned on a thermally stable polyimide layer via pressure-assisted capillary force lithography. The patterned surface provided multi-directional LC alignment condition simply after a unidirectional rubbing process. [ABSTRACT FROM AUTHOR]

We demonstrate the stability-enhanced novel flexible liquid crystal display (LCD) mode by using the micro-structure of rigid columnar spacer array and a micro-contact printing (µCP) assembling method. Specially designed multi-column structure induces self-collected structure of adhesion material which resulted in the good adhesion properties of device to an external deformation as well as enhanced mechanical stability of electro-optic characteristics for flexible display application. Moreover, suggested method can easily inherit most advantages of conventional LCD technology such as low driving scheme, established process and LC mode selection freedom within a simple fabrication procedure. This novel technique can be highly applicable for realizing practical flexible display with enhanced mechanical stability and high performance. [ABSTRACT FROM AUTHOR]

We proposed a patterning method of liquid crystal (LC) alignment layers for producing multi-domain LC structures. It was demonstrated that conventional LC alignment materials could be selectively patterned by controlling the surface wetting properties of a patterning material during micro-contact printing procedures. The proposed patterning method was particularly simple and, thus, easily applicable to several LC devices in enhancing or designing electro-optic properties by using multi-domain LC structures. [ABSTRACT FROM AUTHOR]

We have fabricated the Pixel-Isolated Liquid Crystal (PILC) mode using micro-supporting structures and anisotropic phase separation method. Since the cell gap is sustained by polymer walls and the phase separated polymer layer, this novel structure shows good electro-optic properties having stability against external mechanical distortion. The mechanical stability of this configuration against external forces like pressure and bending is confirmed to be useful for diverse flexible display applications. [ABSTRACT FROM AUTHOR]

We propose a novel microlens array structure in a homeotropic liquid crystal (LC) configuration. The symmetry of molecular ordering in the homeotropic alignment on a circular surface relief structure provides the polarization independent focusing characteristics of the LC microlens. The surface relief structure of poly-dimethylsiloxane (PDMS) supports an initial convex lens driving scheme of the LC microlens as well as easy modification with great aging property. [ABSTRACT FROM AUTHOR]

A preface to the book journal "Molecular Crystals & Liquid Crystals" presented.