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A pixel define layer (PDL) in an organic light emitting diode (OLED) is patterned using a photolithographic process before the deposition of organic layers on top of ITO anode. If the patterning of PDL on OLED panels can be achieved using a black photoresist, the patterning of black matrix (BM) on top of PDL patterns can be omitted by reducing the reflection of ambient light from OLED panels. In this study, we synthesized a series of side-chain-type polyimides as binder polymers of black photoresists and investigated the potential of using the black photoresist for the fine patterning of black PDL on OLED panels.

Smart wearable devices and sensors have been fabricated by screen printing of metal paste as functional circuits since the metal interconnects exhibited much less electrical resistance than other conducting materials such as carbon nanotube or conducting polymers (PEDOT:PSS). In this study, we chose silver particle as conductive material in the form of silver paste and used screen printing to fabricate a stretchable touch screen panel utilizing metal mesh method for the transparent electrode patterning. The rheological study of Ag pastes showed that the binder polymer with high molecular weight and low glass transition temperature (Tg) can stabilize the Ag paste with Ag particle content over 80% by weight. The stretching and bending tests of Ag electrode films obtained by screen printing indicated that good conductivity of Ag electrodes is related to the stability of Ag paste obtained with the high molecular weight binder polymer.

Transparent conducting electrode film is highly desirable for application in touch screen panels (TSPs), flexible and wearable displays, sensors, and actuators. A sputtered film of indium tin oxide (ITO) shows high transmittance (90%) at low sheet resistance (50 Ω/cm2). However, ITO films lack mechanical flexibility, especially under bending stress, and have limitation in application to large-area TSPs (over 15 inches) due to the trade-off in high transmittance and low sheet resistance properties. One promising solution is to use metal mesh-type transparent conducting film, especially for touch panel application. In this work, we investigated such inter-related issues as UV imprinting process to make a trench layer pattern, the synthesis of core-shell-type Ag and Cu@Ag composite nanoparticles and their paste formulation, the filling of Ag and Cu@Ag mixture nanoparticle paste to the trench layer, and touch panel fabrication processes.

Silver nanowires (AgNWs) with high aspect ratio were obtained utilizing a tapered tubular reactor by the polyol process. The tapered tubular type flow reactor allowed us to obtain nanowires in high yield without defects that is generally encountered in a closed reactor due to excessive shearing for a long time. After reaction the AgNWs were precipitated in the aqueous solution with the aid of a hydrogen bond breaker and were recovered effectively without using a high-cost centrifugation process. Dispersion of the AgNWs were used to prepare transparent conducting electrode (TCE) films by a spray coating method, which showed 86% transmittance and 90 Ωsq−1 sheet resistance.

The porous composite scaffolds (PHBV/HA) consisting of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and hydroxyapatite (HA) were fabricated using a hot-press machine and salt-leaching. Collagen (type I) was then immobilized on the surface of the porous PHBV/HA composite scaffolds to improve tissue compatibility. The structure and morphology of the collagen-immobilized composite scaffolds (PHBV/HA/Col) were investigated using a scanning electron microscope (SEM), Fourier transform infrared (FTIR), and electron spectroscopy for chemical analysis (ESCA). The potential of the porous PHBV/HA/Col composite scaffolds for use as a bone scaffold was assessed by an experiment with osteoblast cells (MC3T3-E1) in terms of cell adhesion, proliferation, and differentiation. The results showed that the PHBV/HA/Col composite scaffolds possess better cell adhesion and significantly higher proliferation and differentiation than the PHBV/HA composite scaffolds and the PHBV scaffolds. These results suggest that the PHBV/HA/Col composite scaffolds have a high potential for use in the field of bone regeneration and tissue engineering. [ABSTRACT FROM AUTHOR]

The disadvantages of the poor mechanical properties of polylactic acid (PLA) limit its ability to be used in a wide number of applications. Melt blending of PLA and thermoplastic polyester elastomer (TPEE) has been performed in an effort to toughen the PLA without significant losses in modulus and ultimate tensile strength. In order to enhance the compatibility of PLA and TPEE, a diisocyanate compound was used as a reactive modifier. The thermal and mechanical properties, miscibility and phase morphologies of the blends were investigated. A blend of PLA and TPEE with a modifier does not lead to an important drop in tensile strength and modulus whereas the elongation at break is characterized by a significant increase (above 300%), compared with that of neat PLA and PLA/TPEE. The blends of PLA/TPEE/Modifier were found by thermal and fractured surface analysis to be an immiscible system with the addition of a modifier. However, the relative ductility of PLA/TPEE/Modifier is 34 times higher than that of neat PLA. The brittle fracture of neat PLA was transformed into a ductile fracture by the addition of a modifier. [ABSTRACT FROM AUTHOR]

The effects of the reducing agents of hydrazine (H4N2), sodium borohydride (NaBH4), and triethylsilane (C6H15Si) on the morphologies of gold nanoparticles in the poly(styrene-b-4-vinylpyridine) micelle were studied using small-angle X-ray scattering (SAXS), UV/visible spectroscopy and transmission electron microscopy (TEM). "Cherry" morphology was found in the gold nanoparticles reduced by hydrazine while "raspberry" morphology was found in the gold nanoparticles reduced by sodium borohydride. Hydrazine was more effective in reducing gold nanoparticle in the core of the PS-b-P4VP micelle than sodium borohydride and triethylsilane. The nanoparticles reduced by hydrazine were confined in the core and more regular than those reduced by sodium borohydride and triethylsilane. The possible mechanism leading to these morphological differences was also discussed. [ABSTRACT FROM AUTHOR]

Transparent conductive ITO/Ag/ITO multilayer thin films were successfully deposited on polyethylene terephthalate (PET) substrates by RF sputtering of ITO layer and DC sputtering of Ag layer at room temperature. Electrical and optical properties of ITO/Ag/ITO multilayer films were strongly dependent on the thickness of Ag thin interlayer. The ITO (50 nm)/Ag (17 nm)/ITO (50 nm) multilayer films deposited on PET substrates exhibited lowest sheet resistance (6.7 Ω/□) and highest transmittance (83.2% at 550 nm). Especially, the sheet resistance of ITO/Ag/ITO multilayer films was superior to those of the commercial ITO (150 nm) films deposited on rigid glass substrates at high temperature. The ITO/Ag/ITO multilayer films coated PET substrate could be a good candidate for application to a transparent conductive oxide (TCO) electrode material for large size flexible OLED devices. [ABSTRACT FROM AUTHOR]

Magnetron sputtering has become one of most useful methods for depositing thin films. However this coating technique has low target utilization and target life time. In this paper a new cathode unit was designed and tested with the simulation of magnetic field to extend the life time of target. The Cu target utilization was increased up to 45% compared to the conventional sputtering cathode. The thickness variation of thin films deposited was also improved in this method. Discharge property, thin films thickness and erosion depth were measured for the whole life time of target. These results were compared with the data obtained with a conventional cathode unit used in the magnetron sputter. [ABSTRACT FROM AUTHOR]

X-ray lithography has been used widely for the fabrication of nano/micro structures. This process was applied to the fabrication of barrier ribs with a high aspect ratio for plasma display panel (PDP). The design of X-ray mask and X-ray exposure process were optimized to fabricate highly precise barrier rib pattern for PDP. [ABSTRACT FROM AUTHOR]

Two different polyazomethine-type conjugated polymers, poly(phenoxiazine-3,3'-dihydroxybensidine)(PZ-DHB) and poly(phenoxiazine-2,4-diamino-6-hydroxypyrimidine)(PZ-DHP) containing phenothiazine moiety and azomethine linkage in the main chain were synthesized by Schiff-base polycondensation reactions. The polymer poly(PZ-DHB) was converted to the photosensitive type, through Mitsunobu reaction by incorporation of a photocrosslinkable group, hydroxyhexyloxystyryl-2-pyridine(2-HHSP) into the polymer side chains. The photosensitive conjugated polymer, poly(PZ-DHB)-PS, exhibited both strong fluorescence emission at 555 nm and good patterning property in the standard photolithographic processes. [ABSTRACT FROM AUTHOR]

We fabricated transparent composite films which have good thermal stability, low CTE (coefficient of thermal expansion) and high mechanical properties for flexible OLED substrate. Glass fiber reinforced composite films were made by UV light induced chemical crosslinking of composite materials consisted of glass fiber and UV curable resin in film state. It was noted that the pattern of the reinforce glass fiber had important effect on the optical and mechanical properties of the resulting composite film. The performance of the composite films in the ITO thin film deposition process and subsequent OLED device fabrication was better than those of the known polymer films such as PET, PC, and PES. [ABSTRACT FROM AUTHOR]

A silylated anthracene derivative, bis[2-(p-trimethylsilyl)phenylethynyl]anthracene (1), was synthesized by using Sonogashira reaction. Compound 1 showed two absorption maxia(λmax,abs) at 444 and 447 nm, and fluorescence maximum (λmax,em) at 478 nm. Compound 1 had higher melting temperature of 274°C compared to anthracene 210°C presumably due to confinement of π-conjugated system by trimethylsilyl end-capping, which will be beneficial in the high temperature operation condition of OLED devices. As compared to the commercially available, blue-light emitting, material 4 and tert-butylated compound 2, the compound 1 showed small red-shift of 9 nm in the OLED emission from the by PL λmax due to the increased electron density in the anthracene ring. The compound 1 was also found to be easily fabricated in the flexible OLED devices and showed a low threshold voltage and high current efficiency compared with other anthracene derivatives. [ABSTRACT FROM AUTHOR]

A series of polyimide (PI) and copolyimide (Co-PI) films were prepared by two-step imidization processes from the poly(amicacid) precursors. The color and visible light transmission of the Co-PI films were much better than those of the general Kapton type PI film mainly due to the decrease of the charge transfer complex formation by the presence of the CF3 groups both in the aromatic diamine and dianhydride monomers. In the ITO thin film deposition and subsequent OLED device fabrication, the thermal and mechanical properties of the Co-PI films were more important than the optical property of the Co-PI films. [ABSTRACT FROM AUTHOR]

N-triarylamines, m-MTDAPB and 1-TNAPB, with high glass transition temperature and hole affinity were evaluated as a hole injection layer (HIL) in organic light-emitting diodes (OLEDs) with the configuration of ITO/N-triarylamine/α-NPD (HTL)/Alq3 (EML)/LiF/Al. The performance of N-triarylamines as HIL in OLEDs was investigated in terms of turn-on voltage, luminescence, color purity, etc. Better EL performance was observed in OLED with m-MTDAPB as HIL, showing turn-on voltage of 6 V and maximum luminescence of 2,976 cd/m2 at 13.5 V. This might be attributed to well-matched HOMO energy offsets at the interfaces of anode/HIL/HTL layers in OLED with the configuration ofITO/m-MTDAPB/α-NPD (HTL)/Alq3 (EML)/LiF/Al, compared to OLED with1-TNAPB as HIL. [ABSTRACT FROM AUTHOR]

New copolymers such as Poly(9-(4-(2-ethyl-hexyloxy)-3,5-dimethylphenyl)carbazole-alt-aminonaphtalene) [P1] and Poly(4-(bis-methylbiphenyl-alt-9H-carbazol-9-yl)benzenamine) [P2] with chromophores separated by non-conjugated methylene spacers, and Poly(4-(dioctylfluorene-alt-9H-carbazole-9yl)benzenamine) [P3] based on alternating fluorene and amine units in the polymer backbone were synthesized by palladium catalyzed polycondensation reaction. Optical properties of these polymers were characterized in terms of UV/visible absorption and photoluminescence (PL) emission in solution and film state. Maximum PL emission (λmax,PL) of synthesized copolymers were observed in the blue region of 426 nm-460 nm in solution state, but the three polymers all showed large red shift in film state with the green emission. The electro-optical properties of these polymers in polymer light-emitting diode (PLED) devices were investigated from the viewpoint of utilizing the new polymers as emitting layer and hole injection/transport layer. The polymer P3 was found to function both as hole injection and hole transport layer with performance better than that of well known PEDOT:PSS hole injection layer material. [ABSTRACT FROM AUTHOR]

In this study, we have tried the growth of indium tin oxide (ITO) thin films by using low frequency (60 Hz) magnetron sputtering method (LFMSM). Characteristics of ITO thin films deposited at different substrate temperatures (Ts) from room temperature (RT) to 300°C were investigated. The optical transmittance of more than 83% in the visible region and a resistivity of 1.7 × 10-4 Ω·cm have been obtained in the films prepared at a deposition rate of 100 Å/min. The peak to valley roughness (Rp-v) value measured by an atomic force microscopy was 4.2-7.8 nm. Structural and electrical characteristics are superior in the films deposited at 250°C. The sheet resistance was 11 Ω/sq for 150-nm-thick films grown at 250°C. LFMSM is a way to obtain ITO films with a smooth surface, high transmittance and high electrical conductivity. [ABSTRACT FROM AUTHOR]

A series of N-triarylamine-based derivatives such as 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), 1,3,5-tris[4-(3-methylphenyl(phenyl)amino)phenyl]benzene (m-MTDAPB) and 1,3,5-tris-{4-[1-naphthyl(phenyl)amino]phenyl}benzene (1-TNAPB) were synthesized and characterized. Specially, 1-TNAPB was synthesized with high yield in 1 hr. The hole injecting/transporting properties of these materials were investigated by using double-layered organic light-emitting diodes (OLEDs) with the configuration of ITO/N-triarylamine/Alq3/LiF/Al, in which Alq3 was used as an emitting and electron transporting layer. A comparative study on EL performance of OLEDs fabricated with N-triarylamines as the hole injecting/transporting layer revealed that better results were observed in OLED with m-MTDAPB and α-NPD, respectively. OLED with m-MTDAPB (20 nm thickness) showed maximum luminescence of 15,970 cd/m2 at 10 V and turn-on voltage of 4 V. On the other hand, α-NPD (50 nm thickness) exhibited maximum luminescence of 17,650 cd/m2 at 17 V and turn-on voltage of 7 V. [ABSTRACT FROM AUTHOR]

Flexible white OLED (organic light emitting diode) is a subject of intense research due to its application as versatile lightings for housing and flexible backlight unit for TFT-LCD. In order to make flexible OLED, flexible transparent conductor substrate is required which can replace ITO-glass used in current OLED devices. Another important point is a good gas barrier property of the flexible ITO-film, since the water vapor transmission rate (WVTR) of polymer film is much higher than that of ITO-glass and the life time of OLED device is very sensitive to the transmitted water vapor. In this work, a wet process of forming gas barrier layer on polyethersulfone (PES) film was studied utilizing spin coating of polysilazane solution and thermal conversion to thin SiO2 barrier layer. The flexible white OLED fabricated with this ITO-SiO2 (polysilazane)-PES substrate exhibited about equal power and current efficiencies to the OLED made with ITO-glass. [ABSTRACT FROM AUTHOR]

Novel negative-type photocurable imide UV monomers were synthesized and characterized for an application to interdielectric layer in TFT-LCD array. Two different imide-type UV monomers were synthesized through 2 step reaction. In addition, alkali developable polymer matrix was also prepared by free radical random copolymerization of benzylmethacrylate and methacrylic acid in THF at 65°C. It was found from photolithographic process that via-hole with good resolution were obtained using optimum formulations, suitable for spin coating process, of negative-type imide UV monomers, photoinitiator, UV oligomer, and alkali developable polymer matrix. [ABSTRACT FROM AUTHOR]

We developed a mercury free Flat Fluorescent Lamp (FFL) with a high luminance by using the same discharge mode as PDP. Our FFL has the simple structure where the glass substrates are used as the dielectric layer. The panel has a striped line shape of 7-inch diagonal size. The Xe-Ne-He mixture gas was used to generate the plasma, and the gas discharge characteristics under both total gas pressure and partial gas pressure were investigated. The panel showed a maximum high luminance 7,270 cd/m2 under biasing 20 kHz pulse of 3 kV. [ABSTRACT FROM AUTHOR]

We introduce indium zinc oxide (IZO) thin films grown at room temperature by using a low-frequency (LF) 60 Hz magnetron sputtering system. The flexible substrates are PES, PET and PC. The optical, electrical and structural properties of IZO films on flexible substrates were investigated. The alloy target was In2O3:ZnO (90:10 wt%) with a diameter of 3 inch and thickness of 5 mm. The vacuum chamber was evacuated down to pressure 5 × 10-6 torr prior to deposition. The flow rates of argon gas (99.999 %) were kept at a constant value of 30 sccm by a mass flow controller(MFC). The discharges were performed by power of 300 V, 310 V, 320 V. They have low sheet resistance of about 30 Ω/sq., high transmittance of over 85 % in the range of 400-700 nm. Also they showed good band gap of about 3.43 eV on polyethersulfone (PES) substrates, 3.50 eV on polyethylene terephthalate (PET) and 3.30 eV on polycarbonate (PC). The experimental results imply that the films with good qualities in surface morphology, transmittance and electrical conduction can be grown by a low-frequency magnetron sputtering method an PES is the most recommendable substrate. [ABSTRACT FROM AUTHOR]

In this study, we have tried the growth of indium tin oxide (ITO) thin films by using low-frequency magnetron sputtering method (LFMSM). Characteristics of ITO thin films deposited on polyethersulfone (PES) and polyetyleneterephthalate (PET) substrates are investigated. Experiments were carried out as a function of deposition time. With increasing the deposition time of the ITO thin films on PES substrate, the sheet resistance is decreased. ITO thin films on polymer substrates were amorphous structure. [ABSTRACT FROM AUTHOR]

A dopant, 4,4'-bis(dimethyl[4-(2-phenyl-buta-1,3-dienyl)phenyl]amine) biphenyl (BPAB), was synthesized, and single layered polymer light emitting diode (PLED)s, ITO/Host:Dopant/Al, were fabricated with blends of poly(vinyl carbazole) (PVK) as host and BPAB as dopant. The electroluminescence (EL) was observed in doped PLEDs. From the EL and photoluminescence (PL) spectra, the existence of energy transfer from host to dopant was verified. With increasing content of dopant (BPAB), blue emission originated from PVK reduced, but didn't completely disappear, suggesting inefficient energy transfer from PVK to BPAB. When the content of BPAB was 15 wt%, yellow green emission from PLED was observed due to partial energy transfer from PVK to BPAB. [ABSTRACT FROM AUTHOR]

Poly(1,1'-biphenyl-4,4'-ylene vinylene-alt-2,5-bis(2-ethylhexyl)-1,4-phenylene vinylene] [poly(BPV-alt-BEHPV)] as a polymeric dopant, was synthesized by Honer-Emmons condensation from corresponding dialdehyde and diphosphonate monomers. Synthesized alternating polymer was used to fabricate single layer (ITO/Host:Dopant/Al) PLEDs with poly(vinyl carbazole) (PVK) as a host. Conjugated poly(BPV-alt-BEHPV) showed green emission from single layer ITO/poly(BPV-alt-BEHPV)/Al device. Emission colors from doped PLEDs were changed by energy transfer from blue originated from PVK to green with increasing the content of poly(BPV-alt-BEHPV). [ABSTRACT FROM AUTHOR]

Poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene-co-1,4-phenylene vinylene) (MEH-R) and poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene-alt-1,4-phenylene vinylene) (MEH-A50) containing phenylene vinylene (PV) unit and alkoxyphenylene vinylene (MEHPV) unit in the main chain were synthesized by the dehydrohalogenation and Honer-Emmons reaction using potassium t-butoxide, respectively. Single layer polymer light-emitting diodes (PLEDs) were fabricated with synthesized conjugated copolymers as emitting layers, and their emission properties were compared with PPV and MEH-PPV homopolymers. UV-Visible absorption and EL spectra of MEH-Rs were blue-shifted as increasing the amount of PV unit in the main chain. Color coordinates of single layer PLEDs made with the conjugated copolymers were compared with those of standard red, green, blue, and white established by NTSC. Color coordinates of single layer PLEDs made with MEH-Rs and MEH-A50 were shifted from red (MEH-PPV) to green region (PPV) as increasing PV unit in the main chain. [ABSTRACT FROM AUTHOR]

Conjugated copolymer, poly[N-(2-ethylhexyl)phenothiazine-alt-6-phenyl phenanthridine] [poly(PZ-PTI)], with azomethine linkage was synthesized by Schiff-base reaction. This new conjugated copolymer exhibited improved solubility in common organic solvents due to the presence of alkyl side chains on phenothiazine rings as well as polar azomethine groups in main chains. Single-layered PLED made with poly(PZ-PTI) as an emitting layer exhibited EL (emission) at 572 nm (yellow; color coordinates of x = 0.51, y = 0.48). Double-layered PLED fabricated with the synthesized polymer as an emitting layer and Alq3 as an electron transporting layer exhibited enhanced EL emission and efficiency compared to that of single-layered PLED. With increasing the thickness of Alq3 layer in double-layered PLED the emission peak gradually shifted to the single-layered PLED made with only Alq3 as an emitting layer, confirming good hole transporting behaviour of the synthesized conjugated copolymer. [ABSTRACT FROM AUTHOR]

Alternating copolymers such as P(3,6-EHCZ-alt-Al), P(Bis-EHCZ-alt-Al) and P(2,7-EHCZ-alt-Al), based on blue-emitting carbazole and hole-transporting triarylamine units in the polymer backbone, were successfully synthesized by using palladium-catalyzed polycondensation reaction. P(Bis-EHCZ-alt-Al) exhibited blue shift both in UV-Vis absorption and PL emission, while P(2,7-EHCZ-alt-Al) showed red shift in UV-Vis absorption and blue shift in PL emission, compared to P(3,6-EHCZ-alt-Al). It was observed from the optical and electrochemical characterization that band gap energy (2.91 ∼⃒ 3.07 eV) and HOMO (-5.25 ∼⃒ -5.11 eV) levels of the copolymers could be fine-tuned by the carbazole content in the repeating unit and different reaction linkage on the carbazole ring. [ABSTRACT FROM AUTHOR]

Electroluminescent properties of polymer light-emitting diode (PLED)s fabricated from heterocyclic conjugated random copolymers, poly(PZV-ran-CZV), containing (N-2-ethylhexyl)-3,6-phenothiazinylene vinylene (PZV), (N-2-ethylhexyl)-3,6-carbazolylene vinylene (CZV) and phenylene vinylene (PV) unit as a light emitting layer were investigated. PLEDs made with corresponding alternating copolymers, poly(PZV-PV) and poly(CZV-PV), as a light emitting layer were also studied and exhibited EL maximum at 570 nm and 500 nm, respectively. Single-layered PLEDs made with poly(PZV-ran-CZV) copolymers, however, showed EL maxima shifted to longer wavelength. Double-layered PLED made with poly(PZV-ran-CZV) copolymer as a light emitting layer and Alq3 as an electron transporting layer exhibited enhanced EL emission compared to that of single-layered PLED. [ABSTRACT FROM AUTHOR]

In this work, formulation of photosensitive pastes was investigated to fabricate barrier ribs of PDP by a photolithographic process. Optimum paste compositions could be achieved by the formulation of alkali-developable polymeric binders, functional monomers, a photoinitiator, and a solvent with barrier rib powders of which surface was treated with fumed silica particles. It was applied to the paste and was found that photolithographic patterns of barrier ribs could be obtained with good resolution up to 110 ∼⃒ 120 μm of height and 60 ∼⃒ 80 μm of width after sintering. This could be explained by increased light transmittance efficiency through UV light guide channel formed with an aid of nano-sized fumed silica used for surface treatment of barrier rib powders. [ABSTRACT FROM AUTHOR]

In this study, we introduce indium tin oxide (ITO) thin films grown by using low-frequency (60 Hz) magnetron sputtering method. Characteristics of the ITO thin films deposited on polyethersulfone (PES) substrates are investigated. Experiments were carried out as a function of deposition time and substrate temperature. ITO thin films on PES substrate revealed amorphous structure. The optical transmittance, the sheet resistance and the resistivity of the films decreased with the increasing deposition time. The sheet resistance and the roughness of the films increased with the increasing substrate temperature. Roughness values of ITO films on PES substrate deposited at various substrate temperatures are Ra (<2 nm), Rms (<3 nm) and Rp-v (<10 nm). The experimental results confirm that the films with good qualities in surface morphology, transmittance and electrical conduction can be grown by a low-frequency magnetron sputtering method. [ABSTRACT FROM AUTHOR]

Thermally stable and solution-processable poly(N-arylcarbazole-alt-aniline) copolymers with high structural integrity were synthesized in good yields via palladium-catalyzed polycondensation of aniline with corresponding N-arylcarbazole monomers such as N-(2-ethylhexyloxyphenyl)-3,6-dibromocarbazole, bis[6-bromo-N-(2-ethylhexyloxyphenyl)carbazole-3-yl] and N-(4-(2-ethylhexyl)-3,5-dibromomethylene-phenyl)carbazole, respectively. The optical and electrochemical properties of these copolymers were measured and compared with those of poly(N-alkylcarbazole-alt-aniline) copolymer. All synthesized poly(N-arylcarbazole-alt-aniline) copolymers showed maximum UV-Vis absorption peaks at around 300 nm in THF solution, and exhibited maximum photoluminescence peaks in the blue emission range from 430 to 460 nm. It was also found that poly(N-arylcarbazole-alt-aniline) copolymers had wider band gap energy than poly(N-alkylcarbazole-alt-aniline) copolymer. [ABSTRACT FROM AUTHOR]

Well-defined copolymer, P(3,6-EHCZ-alt-MPAOXD), containing a triarylamine and N-alkylcarbazole groups (as hole transport moieties with blue emission) in the main chain and a 1,3,4-oxadiazole pendant group (as an electron transporting moiety) was synthesized by Pd-catalyzed polycondensation of N-(2-ethylhexyl)-3,6-dibromo carbazole with 2-methylphenyl-5-(4-aminophenyl)-1,3,4-oxadiazole. For comparison, P(3,6-EHCZ-alt-AL) containing a triarylamine and a carbazole groups in the main chain was also prepared. P(3,6-EHCZ-alt-AL) exhibited λmax,UV at 309 nm and λmax,PL in the range of blue emission at 452 nm. However, P(3,6-EHCZ-alt-MPAOXD) exhibited λmax,UV at 283 nm with a new peak at 359 nm, and red-shifted PL emission at 506 nm, possibly attributed to the extended conjugation by 1,3,4-oxadiazole pendant group. The electrochemical results revealed that incorporation of 1,3,4-oxadiazole group in the polymer side chain provided a closely matched HOMO energy levels with hole-injecting PEDOT layer, and reduced the band gap energy level. [ABSTRACT FROM AUTHOR]

A blend of side-chain liquid crystal polymer (SCLCP) and low molecular weight liquid crystal (LMWLC) was used to investigate a phase separation behavior induced by temperature. Phase separation at room temperature was observed only for the compositions higher than 60 wt% LMWLC because of good miscibility between two components. An interesting phenomenon was observed when the film transmittance for a phase-separated sample as a function of temperature was measured under cross-polarizer. That is, transmittance below TNI of LMWLC was observed lower than that below TSI of SCLCP, which was not expected initially. The fact was considered as a micro-phase separation induced by an interfacial effect between SCLCP and LMWLC phase. [ABSTRACT FROM AUTHOR]

A series of poly( N -vinyl carbazole)-based random copolymers containing photosensitive cinnamoyl moieties capable of generating negative type patterned images were synthesized and characterized. First, poly( N -vinyl carbazole- ran -hydroxyethyl methacrylate) copolymers, P(VK- ran -HEMA), were prepared by free radical polymerization of VK and HEMA monomers using AIBN as an initiator in THF. In second step, cinnamoyl groups were introduced by post reaction. Photoluminescent properties of synthesized photosensitive copolymers were measured and, upon UV exposure, negative patterned images with high resolution were produced by standard photolithographic process. [ABSTRACT FROM AUTHOR]

Two types of blue electroluminescent conjugated polymers, poly(BP- alt -BCV) and poly(BFMP12-BPV), were prepared by Horner-Emmons polycondensation and used as host polymers for the phosphorescent dopant, (bsn) 2 Ir(acac). Poly( N -vinylcarbazole) (PVK), known as a blue emitting material, was also used for comparison with these polymers. Electrophosphorescence of PLEDs with these dopant/host systems was investigated in terms of luminescence, efficiency, emission color, and energy transfer. The poly(BP- alt -BCV) showed blue emission of high color purity (x = 0.18, y = 0.19), however, poly(BP- alt -BCV) host/phosphorescent (bsn) 2 Ir(acac) dopant showed red emission (x = 0.60, y = 0.37) due to an efficient energy transfer from poly(BP- alt -BCV) host polymer to phosphorescent (bsn) 2 Ir(acac) dopant. [ABSTRACT FROM AUTHOR]

Novel red phosphorescent iridium complex with two phenyl-isoquinoline ligands and one 2-acetyl-cyclopentanone ligand (IR-PIQCP) was designed and synthesized. The electroluminescent (EL) characteristics of IR-PIQCP were evaluated in the EL device. The three kinds of EL devices were fabricated by the vacuum deposition method, and the layer-structures of the devices were ITO/NPD/IR-PIQCP (5%), IR-PIQCP (10%) or IR-BTPAC (10%) in CBP/Balq/Alq/LiF/Al. Emission characteristics of the IR-PIQCP (5%) and IR-PIQCP (10%) devices were about 570 cd/m 2 and 550 cd/m 2 at 11 mA/cm 2 at the same current density respectively. The EL spectra of the IR-PIQCP (5%) and IR-PIQCP (10%) devices were detected at about 627 nm and 629 nm as the maximum peak with red phosphorescence. [ABSTRACT FROM AUTHOR]

(N-2-ethylhexyl)-3(6)-phenothiazinylene vinylene-co-9,10-anthrylene vinylene), KPD-1, as a new low molecular weight dopant was synthesized. Poly(1,12-dodecanedioxy-2-methoxy-1,4-phenylene-1,2-ethenylene-1,1′-biphenyl-4,4′-ylene-1,2-ethenylene-3-methoxy-1,4-phenylene),[Poly(BFMP 12 –AV)], as a matrix polymer was also prepared by Honer-Emmons condensation. Single- and multi-layered PLEDs were fabricated with a mixture of dopant/matrix polymer as an emissive layer. The effect of dopant/matrix polymer and device structures on the energy transfer and electro-optical properties of doped PLEDs was discussed in terms of emission color changes and luminescence efficiency of doped PLEDs. [ABSTRACT FROM AUTHOR]

Fabrication process of electrophoretic display panels was investigated by utilizing transparent soft mold press, which enables to guide uniform packing of charged TiO 2 particles and colored particles for color e-Paper display. For this process, transparent soft mold was prepared by reacting silicone solution(silicone prepolymer/curing agent&ThickSpace;=&ThickSpace;10/1&ThickSpace;wt./wt.)into the base mold. While pressed with the transparent soft mold under 1.5&ThickSpace;&nvsim;&ThickSpace;3.0&ThickSpace;Kg f /cm 2 of pressure at 60&ThickSpace;&nvsim;&ThickSpace;90°C, the photosensitive film was exposed to UV light at 365&ThickSpace;nm in the range of 800&ThickSpace;&nvsim;&ThickSpace;2,000&ThickSpace;mJ/cm 2 . The transparent soft mold was demolded by rolling up to give electrophoretic display panels with precise geometry. The process of obtaining colored electrophoretic display was also discussed. [ABSTRACT FROM AUTHOR]

Vinylbenzyl abietate (VBA) was synthesized by the reaction of 4-vinylbenzyl chloride with sodium abietate. VBA homopolymer and copolymers of VBA with methyl methacrylate (MMA) were prepared in benzene using azobisisobutyronitrile as an initiator. The compositions of the copolymers were measured with ¹H NMR. The monomer reactivity ratios were determined by Kelen-Tüdös plot. The reactivity of VBA for the copolymerization was much larger than that of MMA. The glass transition temperature and the initial decomposition temperature of the homopolymer were higher than those of the copolymers. The polymers with the abietic acid moiety were crosslinked with UV irradiation. This result means that VBA can be a vinyl monomer for the preparation of photocrosslinkable polymers. [ABSTRACT FROM AUTHOR]

Improved electroluminescent efficiencies in polymer light-emitting diodes(LEDs) have been reported to be obtained either by constructing multi-layer devices or by using polymer blends in a light emitting layer. In this work, conjugated copolymers, poly((PZV-PV)-co-(CZV-PV)) containing (N-2-ethylhexyl)-3,6-phenothiazinylene vinylene(PZV) unit and (N-2-ethylhexyl)-3,6-carbazolylene vinylene(CZV) unit in different ratio were synthesized by Horner-Emmons reaction utilizing potassium t -butoxide. Homopolymers, poly(PZV-PV) and poly(CZV-PV) were also synthesized. Polymer LED's fabricated with poly(PZV-PV) and poly(CZV-PV) homopolymers as light emitting layers exhibited EL maximum at 570 nm amd 500 nm, respectively. LED's made with poly((PZV-PV)-co-(CZV-PV)) copolymers, however, showed EL maxima shifted to longer wavelengths. [ABSTRACT FROM AUTHOR]

Professor Lee-Soon Park of Kyungpook National University, Korea, and Professor Tomiki Ikeda of Tokyo Institute of Technology, Japan, discussed a possibility to have an international symposium on liquid-crystalline materials and devices since Korea and Japan are the leading countries in the field of liquid crystal displays (LCDs) and we believed that it would be quite fruitful for the research scientists in the related fields to come together, presenting their the state-of-the-art results, and discuss their results. We agreed to have the first international symposium on Liquid-Crystalline Materials and Devices (LCMD) on April in 1997 at Kyungpook National University at Daegu in Korea, in which the participants were mainly from Korea and Japan. The first international symposium was so successful that we decided to have the second symposium in Japan (LCMD98) in 1998. Since then, we have had international symposiums alternately in Korea and in Japan every year. In 2003, we decided to include other topics related to display materials and devices such as electroluminescence and organic light-emitting diodes, and changed the name of the symposium to “International Symposium on Advanced Display Materials and Devices (ADMD)”. In 2004, we had the ADMD2004 at Himeji in Japan, which Professor Nobuhiro Kawatsuki organized, and had many participants not only from Korea and Japan, but also from USA and China. This volume presents the Proceedings of the ADMD2004 held in Himeji on September 23 and 24, 2004. ADMD2004 was sponsored by the Grant-in-Aid for Scientific Research (S) (No. 16105004) from the Japan Society for the Promotion of Science (JSPS) under the auspices of the Japanese Liquid Crystal Society, The Society for information Display, Korea Chapter, The Korean Society of Industrial Engineering Chemistry, Information and Electric Materials Division. We had 101 participants and 46 presentations including 15 oral presentations and 31 poster presentations. The ADMD2004 was organized successfully, which was owing to the help of many people: participants, reviewers of the papers submitted to this special issue and also to Ms Concetta Seminara-Kennedy, the Management Editor of this volume for minute editing. June 2005 Tomiki Ikeda Lee-Soon Park Nobuhiro Kawatsuki (Guest Editors) [ABSTRACT FROM AUTHOR]

A foreword to the journal "Molecular Crystals & Liquid Crystals" is presented.

A foreword to "Molecular Crystals & Liquid Crystals" is presented.