Search

Epoxy acrylate (EA) resin, which originates from epoxides, has long been served as a photocurable coating and adhesive material owing to its double bonds. Specifically, alkaline-developable EA resins can be used as a binder polymer in negative-tone photoresists. In this work, we synthesized a series of acidic polyester-type epoxy methacrylate resins, characterized the intermediates and products, and tested their performance as a binder polymer for the photolithographic micro-patterning of the pixel-defining layer on organic light-emitting diodes in comparison to a widely used commercial binder polymer. Copolymer-type binder polymer BP-2-2 was produced excellent patterning with no residue due to its high compatibility with the black mill base.

Polyimides are well-known for their high chemical inertness and thermal stability. However, it is usually challenging to synthesize UV-curable polyimides since the imidization reaction requires such harsh conditions that acrylate type double bonds cannot withstand. In this work, synthetic methods are developed to obtain polyester-imide type binder polymers with high thermal stability, high compatibility with the other components of the black photoresist, and fine photolithographic patterning property for the negative-tone black photoresist. The syntheses of diimide-diacid or diimide-diol intermediates for the polyesterification with dianhydride gave polyester imides which meets this requirement. The photolithographic tests have shown that the patterning of the micron-sized PDL of the organic light emitting diode (OLED) panel could be obtained. This work will interest the researchers working on the design and optimization of thermally stable binder polymers.

The fabrication of black pixel define layer (PDL) on the organic light emitting diode (OLED) panel has been developed actively by using negative-tone black photoresist which contain photoinitiator, photosensitizer, binder polymer, multifunctional monomer and black mill base in order to improve the outdoor visibility of OLEDs. Cardo type binder polymer containing bulky and rigid fluorene group has been widely used in the black photoresist formulation. However, the commercial cardo binder polymer has high cost and requires high UV dose for the fine patterning of PDL in the photolithographic process. In this study we designed and synthesized various non-cardo type binder polymers and evaluated the new binder polymers in comparison with the cardo binder polymer for the improved patterning of PDL on the OLED panel.

Smart phones have become one of major electronic devices for human being. The easy and rapid exchange of information between man and machine is carried out by the touch screen panel (TSP) installed in the smart phones. Currently the smart phones are widely spread out while displays for automobiles are in the initial stage of developments. Since the automobile displays should fit the curved area of indoor space of the vehicle, the TSPs for automobiles need to be fabricated on the flexible and stretchable substrate film. In this study, we selected the thermo-plastic polyurethane film as the substrate film and examined the materials and process for fabrication of metal mesh type transparent conducting electrode films suitable for TSPs of automobile displays. The optimum UV resin system was established by the evaluation of various UV resin formulations in the UV imprinting process to make 3 × 3.5 μm trench patterns on the metal mesh type electrode film utilizing the embossed metal mask plate. The Ag paste has also been prepared by synthesis of Ag nanoparticles and formulation with the binder polymers. The inlay (filling) of Ag paste in the trench layer of transparent electrode film showed that the variation of electrical resistance was within 10% upon bending up to 100,000 times to radius of 3 mm.

Polyimides are well known for their high chemical and thermal stability. However, a few polyimide samples have been reported which are completely soluble in such environmentally friendly and common organic solvent as propyleneglycol monomethyl ether acetate (PGMEA). In this work thermally stable, organosoluble and photocurable acidic polyimides were synthesized by simple and cost effective one-pot solution method. They polyimides obtained by this method showed much higher thermal stability (1 wt% loss temperature 345°C) than melt polymerized polyimides owing to the photocrosslinking reactions by the terminal double bonds.

Organocatalysed photoredox-mediated atom transfer radical polymerization (O-ATRP) is a very promising polymerization method as it eliminates concerns associated with transition-metal contamination of polymer products. However, reducing the amount of catalyst and expanding the monomer scope remain major challenges in O-ATRP. Herein, we report a systematic computer-aided-design strategy to identify powerful visible-light photoredox catalysts for O-ATRP. One of our discovered organic photoredox catalysts controls the polymerization of methyl methacrylate at sub-ppm catalyst loadings (0.5 ppm—a very meaningful amount enabling the direct use of polymers without a catalyst removal process); that is, 100–1,000 times lower loadings than other organic photoredox catalysts reported so far. Another organic photoredox catalyst with supra-reducing power in an excited state and high redox stability facilitates the challenging polymerization of the non-acrylic monomer styrene, which is not successful using existing photoredox catalysts. This work provides access to diverse challenging organic/polymer syntheses and makes O-ATRP viable for many industrial and biomedical applications. Organocatalysed photoredox-mediated atom transfer radical polymerization is a very promising method, although many challenges still lie ahead. Now, Kwon, Gierschner, Kim and co-workers present a computer-aided-design strategy to identify organic photoredox catalysts for this process. The success of the design strategy is demonstrated by polymerizations of methyl methacrylate and styrene.

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.

Organic light emitting diode (OLED) is widely used as displays for small devices like cellular phone, tablet and wearable devices as well as large devices like TV. Photolithography utilizing black ...

Strain sensors for human-motion detection must offer high stretchability, high sensitivity, fast response, and high recovery speed. In this study, we choose silver paste as a sensing material and use a screen printing method to fabricate the strain sensor based upon an electrical-resistance mechanism. After curing elastomeric polyurethane film with a thickness of 150 μm on PET film, the polyester resin mixed with blocked isocyanate curing agent was coated as a masking layer to reduce the film’s stickiness. The effect of the polyester masking layer upon the silver paste screen printing process was examined using a rolling-ball-tack test, TGA analysis of polyester resins, and cured silver-electrode films. The cost-effective strain sensor fabricated by using silver paste and screen printing processes on the stretchable-polyurethane-substrate film showed high sensitivity and fast response in a strain range of up to 100%.

In order to improve the visibility for outside use of organic light emitting diodes (OLEDs), the polarized film and black matrix pattern have been used in the small and medium sized OLEDs; however, these cause problem of reducing the emission efficiency of OLED. Changing the color of pixel define layer (PDL) from brown to black is an important point for improving the efficiency and visibility of OLEDs. In this work we studied the photoresist material containing black pigment and the photolithographic process for patterning of black PDL on OLEDs. The black PDL patterns made with our synthesized polyimides as thermal stabilizer were found to give high thermal stability over 300°C.

In this work core-shell type Ag-metal oxide particles were synthesized by coating of Ag metal on the surface of SiO2, ZnO and TiO2 particles utilizing alkylamine silver complex as Ag source. The re...

Flexible organic light emitting diodes (OLEDs) have been studied actively for the potential application to OLED display and OLED lighting. One of the key materials for flexible OLED is the flexible and transparent film substrate which can substitute ITO glass in flat panel OLEDs.In this work we deposited silicon and aluminium oxide and nitride single layer thin films on different flexible substrates such as poly(polyethylene terephthalate) (PET) and poly(polyethylene naphthalate (PEN) to investigate the gas barrier properties. After selecting the polymer film substrate and thin inorganic layer material, the inorganic/organic/inorganic multiple gas barrier was formed on film substrate by using roll-to-roll sputter and their property was examined from the viewpoint of multilayer structure and gas barrier properties for application to flexible substrate of OLED devices.

The efficiency and life time of flexible OLED are still major problem to overcome compared to the OLED devices based on glass substrate. The short life time of flexible OLEDs are attributed to the increased penetration of oxygen and water vapor to the thin organic layer of OLED device through the flexible polymer film substrate.In this work, we prepared glass fiber reinforced polymer film (GFRF) for use as substrate of flexible OLED. The glass fabric was immersed in the UV curable resin and packed between the transparent glass templates followed by UV irradiation for conversion to GFRF. The optical and mechanical properties of the GFRF films were examined and optimized for use as substrate of flexible OLEDs. The gas barrier layers were formed on the GFRF films. The deposition of ITO/Ag/ITO transparent conduction anode was carried out by using roll-to-roll sputter followed by fabrication of flexible OLEDs. The effect of process conditions on the property of flexible OLEDs were studied from the view point o...

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.

The packaging process of white light-emitting diodes (WLEDs) take a relatively long time, even when utilizing an automated dispensing system. Therefore the silicone-based packaging formulation and control of rheology during the packaging of LEDs are very important. The effect of phosphor settling during the curing state of LED packaging has been reported. In this work we studied the effect of phosphor paste on the dispensing stage of the WLEDs packaging process utilizing nanosilica particles as viscosity modifiers. With nano-silica in the silicone resin the sedimentation of YAG phosphor particles were effectively blocked and a uniform distribution of YAG phosphor in the cured silicon resin could be achieved. We also examined the incorporation of red quantum dots (QDs) to improve the color rendering index of the WLEDs with the aid of nano-silica as a rheological additive. The application of nano-silica in the layer-by-layer type encapsulation of red QDs was found to be effective in WLEDs packaging, which improved the color rendering index with warm white emission.

In this work a clear polyimide (PI) film was synthesized by using selected monomers containing multiple CF3 groups. The polyimide-graphene composite films were made by film coating of mixture of polyamic acid (precursor of polyimide) solution with reduced grapheme oxide. The flexible OLEDs were fabricated by using the polyimide-graphene composite films on which the ITO/Ag/ITO thin films were deposited by roll-to-roll sputter instead of usual ITO-glass and the properties of flexible OLEDs were examined from the viewpoint of flexible substrates.

Touch screen displays have been a subject of growing interest in recent years due to the significant usability benefits they provide for portable electronic devices ranging from mobile phones to tablet PCs. In this paper we report the preparation of index-matched ITO-PET films by depositing thin films of SiNx, SiOx and ITO on hard coated polyethylene terephthalate (PET) film utilizing roll-to-roll sputtering system.

Among many display devices, organic light-emitting diodes (OLEDs) have been regarded most promising for the transparent flexible displays. In this work we fabricated transparent flexible OLEDs by adopting ITO/Ag/ITO multilayer as anode and Ag/Al thin film as cathode on PEN film and examined their performances.

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 Omega sq(-1) sheet resistance.

The preparation method of encapsulating paste containing YAG phosphor and red quantum dot (QD) in silicone resin and the structure of phosphor layers were studied from the view point of improving both the efficiency and color rendering index (CRI) of the phosphor converted white LED (pcWLED). The addition of red phosphor or red QD in addition to the YAG phosphor could increase CRI of the pcWLED, but the efficiency was decreased. The pcWLED packaged with the encapsulant where the red QD was mixed in advance with the part of the silicone resin and mixed again with the YAG phosphor dispersed the remaining in silicone resin exhibited higher CRI and efficiency than the one packaged with one pot mixture of YAG and red QDs. The pcWLEDs made by silicone encapsulant with YAG phosphor and red QD at the ratio of YAG:QD = 5.0:0.5wt% exhibited that both efficiency and color rendering index could be increased at same time by adopting YAG phosphor and QD encapsulation in a layer-by-layer structure on top of InGaN LED chip.

The chip on board (COB) types LED modules were fabricated by using metal core printed circuit board (mcPCB), aluminium oxide (Al2O3) and aluminium nitride (AlN) as submounts of LED chips. The radiant flux of the LEDs exhibited slight difference in terms of the LED chip bonding process in which eutectic bonding gave higher radiant flux than Ag epoxy bonding in both AlN and Al2O3 substrates. However the LED modules fabricated on AlN ceramic substrate exhibited higher radiant flux than the one on Al2O3 substrate at high current due to more effective heat dissipation in case of AlN substrate. The WLED modules encapsulated with YAG phosphor and red QD by layer-by-layer mode showed both high total luminous flux and high color rendering index.

From a technical perspective, the major limiting factors for the wide adoption of CNT films are the DC conductivity, uniformity of sheet resistance and good adhesion of CNT on film substrate. In this study, the effects of sonificator and process time on the zeta potential and sheet resistance of the CNT-PET film show that although the dispersing power of horn-type sonificator is stronger than that of bath-type, the SWCNT solution obtained with horn-type sonificator agglomerates faster. Likewise, it has been noted that the SWCNT solutions with low enough zeta potentials exhibit higher sheet resistance after making CNT-PET films due to the damage to SWCNTs caused by high dispersion force. Since the spray coating of SWCNT solution gives the SWCNT-SDS composite layer on PET film after drying, the excess SDS should be washed off. The removal of excess SDS was conducted by dipping in the 3 N HNO3 and SOCl2 solution and washing with deionized water followed by heat treatment in a 120 degrees C convection oven for 30 min. The lift-off of SWCNT-SDS composite layer after 40 min dipping in the 3 N HNO3 solution appeared to be due to the continued permeation leading to swelling of the SDS layer by the 3 N HNO3 aqueous solution. It was found that ten times of spray coating cycle gave CNT-PET film the sheet resistance of 310 Ω/[square] and transmittance of 81%. The TSP made with CNT-PET film exhibited a performance equal to the one made with ITO-PET film.

Highly stable and luminescent InP/GaP/ZnS QDs with a maximum quantum yield of 85% were synthesized by in situ method. The GaP shell rendered passivation of the surface and removed the traps. TCSPC data showed an evidence for the GaP shell. InP/GaP/ZnS QDs show better stability than InP/ZnS. We studied the optical properties of white QD-LEDs corresponding to various QD concentrations. Among various concentrations, the white QD-LEDs with 0.5 mL of QDs exhibited a luminous efficiency of 54.71 lm/W, Ra of 80.56, and CCT of 7864 K.

Organic (Alq3) film, which was coated on a donor plate, was transferred to an organic light emitting diode (OLED) substrate with help of heat generated by a dithering laser beam. The laser beam was diffracted in an acousto-optic modulator (AOM), then focused on the laser-to-heat converting layer of the donor plate; the focused spot followed trajectories guided by rotation of a Galvano-mirror. Three different functional waveforms, sine wave, square wave, and saw tooth wave were applied to the AOM as modulation signal to generate the dithering beam. The fluorescence microscope images of the donor plate showed that the patterns of removed Alq3 film were affected considerably by the modulation waveforms and the phase difference between adjacent dithering beams. Further, the printed images of Alq3 film on the OLED substrate were different from the patterns of removed Alq3 film. Atomic force microscope images indicated that not only direct transfer but also deposition by sublimated vapor of Alq3 contributed to the pattern formation. Printed patterns affected considerably the electricity-to-light conversion characteristics of OLEDs. For uniform transfer, not only the phase relation of dithering beam lines but also adequate waveform were important.

In order to ensure long lifetime and stable light output of LEDs the thermal performance parameters need to be designed in the LED chip package and module level, which include such items as heat sink structure and materials, interface materials and substrates. In this work we used aluminium nitride(AlN) as submount of LED chips and made chip on board(COB) type LED module. The effect of different silver(Ag) epoxy bonding materials and bonding methods on the performance of LED module were examined. The effect of addition of red quantum dot(QD) on the performance of white LED was also studied.

The fluorene-based poly(dioctylfluorene-alt-biphenylamine)s with styrylpyridyl group were synthesized by using Pd-catalyzed polycondensation reaction. These hole injection/transport polymers showed very good solvent resistance after photo-crosslinking which could facilitate the subsequent spin coating of the emitting layer polymer solution. Moreover these polymers could be patterned by using distyrylpyridyl alkyl monomer (DSM) as crosslinking agents. The OLED devices with configuration of ITO/HIL/Alq3:NPD/LiF/Al in which synthesized polymer was used as hole injection layer (HIL) were fabricated and their performance was compared with the commercially available PEDOT:PSS as HIL layer.

In this paper we discussed the effect of micro lens array(MLA) pattern fabricated on the glass substrate of organic light emitting diode(OLED) for improvement of light extraction efficiency. The MLA patterns were formed by combination of photolithography and thermal reflow method and its effect on light extraction efficiency form OLED device was examined.

In this study, we made flexible OLED's based on polyethersulfone(PES) film which has high transmittance in visible region and high glass transition temperature(Tg 223°C). UV hand coating was conducted on the PES base film followed by SiO2 gas barrier layer and aluminium gallium Zinc Oxide(AGZO)/Ag/AGZO transparent multi layer anode by roll-to-roll sputtering. The SiO2 gas barrier was found to be more effective than the UV hand coating as well as enabling the AGZO/Ag/AGZO multilayer anode deposition by roll-to-roll sputter. The relatively high luminance and current efficiency of the flexible OLED with AGZO/Ag/AGZO multilayer anode could be explained by the decreased energy level close to that of NPB hall injection Layer as well as the micro cavity effect of the multilayer anode and gas barrier layer.

In this paper we studied switchable mirrors for application to transparent flat panel displays. The typical structure of switchable mirror has configuration of MgNi/Pd/Ta2O5/HxWO3/ITO. In this study photocatalyst layer (TiO2 or Nb2O5) was used between Pd and Ta2O5 layers. These layers were prepared by RF magnetron sputtering method utilizing TiO2 and Nb2O5 targets under various conditions and their electrochromic properties were investigated by using FE-SEM, EDAX and Nano View system. The transmittances of the Nb2O5 and the TiO2 thin films, could be optimized in the switchable mirror as photocatalyst layer, where they were deposited under the power of 80 W and 70 W, respectively, by the RF magnetron sputter. The characteristics of Nb2O5 and TiO2 transmittance are the outstanding at 80 W, 70 W respectively.

The enhancement of light extraction efficiency is observed when the hole-shape patterned ITO ohmic contact layer and AgIn reflector is adopted in GaN-based flip-chip (FC) light emitting diodes (LEDs). ITO layer (140 nm) and AgIn (200 nm) was deposited on the top of p-GaN by in-line DC sputtering and electron beam evaporating system, respectively. The ITO ohmic contact layer showed a low specific contact resistance of 2.66 x 10(-5) Omega cm(-2) and high transmittance of >85% at visible spectral regions. The AgIn reflector exhibited a low specific contact resistance of 1.90 x 10(-5) Omega cm(-2) and high reflectance of approximately 84% at visible spectral regions. Comparing with unpatterned ITO/AgIn layer, the optical output power of GaN-based FC LEDs improves approximately 30% by the adoption of micro size hole-shape patterned ITO ohmic contact layer and AgIn reflector.

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.

Electrospinning has recently emerged as a leading technique for the formation of nanofibrous structures made of organic and inorganic components. In this study, nanofibrous scaffolds were prepared by electrospining a bend solution of poly(L-lactide-co-glycolide) (PLGA) and silver nanoparticles in 1,1,1,3,3,3,-hexafluoro-2-propanol (HFIP). The resulting fibers ranged from 420 to 590 nm in diameter. To evaluate the possibility of using silver-containing PLGA as a tissue engineering scaffold, experiments on cell viability and antibacterial activity were carried out. As a result, PLGA nanofibrous scaffolds having silver nanoparticles of more than 0.5 wt% showed antibacterial effect against Staphylococcus aureus and Klebsiella pneumonia. Furthermore, silver-containing PLGA nanofibrous scaffolds showed viability, indicating their possible application in the field of tissue engineering.

The effects of the reducing agents of hydrazine ( H 4 N 2), sodium borohydride ( NaBH 4), and triethylsilane ( C 6 H 15 Si ) 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.

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.

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.

Silver (Ag) electrodes with a high resolution and a low edge curl dimension for plasma display panels were successfully fabricated through a photolithographic process using photosensitive Ag pastes with several polymeric binders. The gap and line resolutions of the photosensitive Ag pastes were examined as a function of the molecular weights and acid values of the acrylic binders with carboxylic acid groups. The effect on the formation of edge curls was also investigated with dry- and wet-processed Ag powders. Ag electrode patterns with a line resolution of 20 μm, a gap resolution of 40 μm, and an edge curl dimension of 0.8 μm could be achieved with the developing process in 34.5 s (break point × 1.5) when the photosensitive Ag paste was prepared with the polymeric binder with a molecular weight of 23,320 g/mol and an acid value of 94.98 mg of KOH/g of polymeric binder and with dry-processed Ag powder. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

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,...

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.