The authors have systematically investigated the surface wettability controllable polyimides by UV light irradiation using the polyimides having long-chain alkyl or bulky alkyl groups on their side chains. In this paper, the effects of the addition of photoacid generator or photobase generator were examined. As a result of examining the UV light irradiation (λmax; 254 nm) onto the polyimides based on the diamine monomer having long-chain alkyloxy groups and phenyl ester linkage (12G1-AG-terphenyl diamine), it was proven that the addition of the photoacid generator was effective for the surface wettability control from hydrophobicity to hydrophilicity. On the other hand, the addition of photobase generator was not effective. Therefore, it is speculated that the photoreaction activated by the acid catalyst such as an acid catalyzed ether cleavage and acid catalyzed photo-Fries rearrangement enhance the generation of hydrophilic groups such as a hydroxyl groups after UV light irradiation. In case that the suitable photoacid generator were selected, the surface wettability control of these polyimides by UV light irradiation (λmax; 365nm) were accomplished. The utilization of the UV light (λmax; 365 nm) is the merit in the practical use. From the result of ATR analyses, it is recognized that the hydrophobic alkyl groups on the polyimide surface decrease and the hydrophilic groups such as hydroxyl groups generate on their surface.

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A coexistence with normal and reverse scattering modes is demonstrated in a single liquid crystal (LC) cell by using a polymer stabilized effect. The homogeneously oriented or twisted LC cell containing a small amount of reactive mesogen is exposed with UV light under a suitable curing voltage application. A light scattering state is obtained and it becomes clear by applying voltage. The cell fabricated without the curing voltage shows a reverse mode property, that is, a transparent voltage off-state and the light scattering on-state. A driving voltage of the normal mode is almost the same as that of the reverse mode. A domain with the normal mode property is successfully fabricated in the reverse mode LC cell by two step UV exposures through a photomask with and without the curing voltage. Scattering and transparent patterns simultaneously turns to transparent and scattering states without electrode partitions.

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Polymer-stabilized ferroelectric liquid crystals (PSFLCs), in which photocurable mesogenic monomers are doped into ferroelectric liquid crystals and UV photocure is carried out in the SmA phase, can show the monostable electrooptical characteristics. In this research, we have investigated the dependence of the electrooptical characteristics of PSFLCs on the ratio of binary mixture of monomers. As a result, it is found that the polymer anchoring strength of acrylic acid which does not have mesogenic moiety can be almost ignored, and the polymer anchoring strength of the binary mixture of mesogenic monomer and acrylic acid can be controlled by the variation of their ratio.

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Novel nano-structure for the improved light extraction efficiency of reduced evanescent mode OLED devices (REM OLED) was developed. The nano-structure was designed to have high transmittance especially over critical angle in order to achieve good combination with the light distribution pattern of the REM OLED devices. In this system, the wide angular substrate mode was efficiently converted into the external mode, and high efficacy green OLED with EQE of 54 % was obtained. Relative light extraction efficiency to a hemisphere lens system was 89 %.

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OLED lighting is the promising technology that makes the future lighting more valuable one. For OLED lighting to penetrate into market, considerable challenges remain. From ecology perspective, it is critical to improve the luminous efficacy. White OLED device with the world highest record of 139 lm/W (CCT = 2857 K) at 1,000 cd/m(sup>2 was successfully achieved by introducing proprietary blue phosphorescent emitter to raise the internal quantum efficiency and improved internal extraction structure to enhance the light out-coupling efficiency

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We can conclude that not only a TADF emitter consisting of an intramolecular donor-acceptor structure but also a carrier-transporting material with high triplet energy and high stability is essential to realize highly efficient and stable PHOLEDs with a reduced amount of emitters.

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We compared solution-based spin and blade coating methods in fabrication of organic light-emitting devices (OLEDs). The effect of F8BT film morphology, prepared by two different methods, on device performances was studied in detail. The film morphology and molecular packing arrangement of the F8BT films were investigated by atomic force microscopy (AFM), X-ray reflectivity (XRR), and X-ray diffraction (XRD). We found that the device performances are dependent on evaporation condition of solvent during the formation of the organic layer.

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We have fabricated a pressure-sensing sheet device using a CNT-TFT matrix array, this is the first demonstration of tracing a moving object with CNT active-matrix backplanes.

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A solution-processed a-IGZO TFT was fabricated at 300 °C for 6 min using MW and photoirradiation. Photoirradiation enhanced the on current and the on/off current ratio. The improvement in the TFT performance was attributed to the removal of the organic residue in the IGZO film, leading to the decrease in the charge trap.

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In this study, we fabricated a flexible, stretchable glucose-biofuel cell with silver nanowires (AgNWs) on a dimethylpolysiloxane substrate. The biofuel cell investigated consists of a porous carbon anode (area of 30 mm²) modified by glucose oxidase and ferrocene, and a cathode (area of 30 mm²) modified by bilirubin oxidase. The anode and the cathode were connected with AgNWs. The maximum power of 0.29 μW at 180 mV, which corresponds to a power density of 0.98 μW/cm², is realized by immersing the biofuel cell in a phosphate buffer solution with a glucose concentration of 100 mM, at room temperature.

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A bis-tridentate ligand with 2,6-bis(phenylamide)pyridine moieties (L1) was synthesized by amidation and Suzuki-Miyaura cross coupling reaction from chelidamic acid monohydrate. Novel metallo-supramolecular polymers containing iron(II), ruthenium(II), or nickel(II) ions (PolyFeL1, PolyRuL1 and PolyNiL1, respectively) were obtained as yellowish brown solid via complexation of L1 with the metal ions in the presence of a strong base. The polymers were characterized by IR, UV-vis-NIR absorption spectra, and cyclic voltammetry (CV). The IR spectra showed disappearance of NH stretching peak and shift of C=O stretching peak due to the complexation. The characteristic LMCT absorption appeared at 470 (Fe), 442 (Ru), or 367 (Ni) nm. The solution of the polymers showed a reversible redox wave attributed to the redox of metal ions. PolyFeL1 exhibited reversible electrochromism between orange and brown by applying + 3 V or 0 V.

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The TSC measurements obtained in this study indicate that electrospun fibrous PDLLA films exhibit spontaneous polarization, owing to the presence of a strong electric field applied to the PDLLA solution while forming the fibers. However, an amorphous PDLLA film formed by spin-coating did not exhibit any polarization. The unique polarization characteristics exhibited by the electrospun PDLLA film appeared to contribute to its piezoelectric-like properties.

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The performance of bulk heterojunction (BHJ) organic photovoltaics (OPVs) based on an amorphous polymer, poly(3HTBT-TPA), and fabricated using either halogenated or non-halogenated solvents was investigated. All the BHJ OPVs exhibited almost the same power conversion efficiencies of around 2.2%, indicating that their performance is independent of the casting solvent. These experimental results indicate that the use of amorphous π-conjugated polymers in the fabrication of BHJ OPVs offers two advantages over the use of polycrystalline π-conjugated polymers: highly reproducible OPV performance and the possibility of an environmentally friendly process for fabricating OPVs.

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Bulk-heterojunction solar cells were fabricated using ternary blend dichlorobenzene solutions of poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7):[6,6]- phenyl-C61-butyric acid methyl ester (PC₆₁BM):[6,6]-phenyl C71 butyric acid methyl ester (PC₇₁BM) with different weight ratios between PC₆₁BM and PC₇₁BM. In all the solar cells, the overall weight ratio of polymer to fullerene was maintained at 1:1.5, while the composition of the fullerene component (PC₆₁BM:PC71BM) was varied. The ultraviolet-visible absorption spectra of these ternary blend films showed that the photon absorptions at wavelengths between 300 and 800 nm continuously decreased with the increase of the PC₆₁BM weight fraction in the PC₆₁BM and PC71BM total weight. The measurement results of the solar cell performance showed that the open-circuit voltage notably increased for PC₆₁BM weight fractions between 10% and 90%, while it decreased at 100%. The short-circuit current showed the most significant increase in the PC₆₁BM weight fraction range between 50% and 60%. A power conversion efficiency of 3.4% was achieved when the PC61BM weight fraction was between 50% and 60%. These results may suggest that the transport of the photoexcited electrons between the cathode and the PC61BM/PC₇₁BM nanodomains was enhanced.

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Benzobisthiadiazole (BBT)-containing donor-acceptor polymers were investigated as semiconductors in bulk-heterojunction organic solar cells. Taking advantage of the polarity change of the BBT-based copolymers in terms of comonomer structures, they were examined as both p-type and n-type semiconductors. In the case of n-type semiconductors, fullerene-free organic solar cells were fabricated. A power conversion efficiency (PCE) of 0.02% was achieved when fluorenyl hexa-peri-hexabenzocoronene (FHBC) was employed as a p-type semiconductor. The limited performance might be due to the strong intermolecular π-π stacking of BBT-based copolymers, resulting in the poor miscibility between the donor molecule and acceptor polymer.

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A hot-plate annealing is often used as the anneal process of a regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT): [6,6]-phenyl-C₆₀-butyric acid methyl ester (PCBM) thin-film solar cell. In laboratories, the anneal procedure is carried out by putting the substrates on a hot plate. We tried to anneal the specimens using the Joule heat due to applying current to ITO electrode. The configuration of ITO electrode is 29mm-length and 2mm-width. The current flowing in ITO is from 60 to 80 mA. The temperatures corresponding to these currents are ∼ 95 and ∼140°C. The temperature change of the specimen on a hot plate can be restaged by the Joule heating. Although the photovoltaic properties of non-annealing specimen are the poorest of the three, those of Joule heat annealing specimen are the same as those of hot-plate annealing specimen. The absorption spectra of three specimens are same. The IPCE spectrum of non-annealing specimen is 70 % lower than the other specimens. This result shows the carrier transport in the active layer and the carrier ejection from the active layer to both electrodes. The Joule heat anneal is found to give the P3HT:PCBM device performance similar to the hot plate anneal.

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We successfully fabricated an ellipsoid TiO₂ nanoparticle based DSSC device, with an energy conversion efficiency of 7.2% under AM 1.5 simulated full sunlight (100 mW cm^-2).

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We successfully fabricated, after 7 days of ball milling, a useful aqueous TiO₂ ink with average particle size 250 nm. The tail of the ink droplet merged with the main drop and formed a single droplet when V_p = 17 V was applied to the ink head of the piezoelectric inkjet printer. A clear T-wave pattern was successfully printed out with the aqueous TiO₂ ink.

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We developed a new negative type photosensitive material with the phenolic resin. The film of the material cured at 260^oC showed low coefficients of thermal expansion (CTE), low residual stress and good heat resistance. And the material exhibited good lithography performance. Thus, we expect application of this material to 3D packaging which requires low CTE and low residual stress by low temperature curing.

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In order to simplify the wafer-scale fabrication of microfluidic devices JSR has developed a photo-patternable and adhesive (PA) material which allows to pattern and bond microfluidic structures in one single process step. Control over the film thickness and excellent patterning properties are crucial for many microfluidic applications. By optimizing the acid diffusion after exposure, improved PA patterning properties were achieved. This in combination with the possibility to pattern 80 μm thick structures makes PA an ideal material candidate for many microfluidic and BioMEMS applications.

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The power output of dye-sensitised solar cells and Perovskite solar cells were evaluated under simulated indoor condition. Photopolymers were used to encapsulate the both types of photovoltaic devices which might not be otherwise thermally sufficiently stable. More than twice higher external quantum efficiency was confirmed than measurement under simulated sunlight whilst maintaining photovoltage, leading to up to nearly 20% power conversion efficiency.

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A new type of hyperbranched polyurethane terminated by carboxyl groups (HBP-COOH) has been synthesized by thiol-ene “click” reaction. The carboxyl groups of HBP-COOH were further modified by glycidyl methacrylate at different feed ratio to produce a series of hyperbranched polyurethane acrylate oligomers containing carboxyl groups (HBPUA-COOHs). The structures of products were characterized by FT-IR, ¹H-NMR spectroscopy and gel permeation chromatography (GPC). The photosensitive groups of these synthesized HBPUA-COOHs were measured with UV-Vis spectrophotometer. It was shown that the HBPUA-COOHs had sharp absorption bands at about 205 nm. The photosensitivities were characterized by FT-IR with different curing time. The thermal properties of samples were characterized by DSC and TGA. In addition, the solubilities and viscosity of the HBPUA-COOHs were also examined. These synthesized hyperbranched polyurethane acrylate oligomers containing carboxyl groups, which have well-defined structures with very narrow polydispersities, can be used in many fields such as coatings, adhesives and photoresists, ect.

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From a ternary gaseous mixture of cobalt tricarbonyl nitrosyl (Co(CO)₃NO), iron pentacarbonyl (Fe(CO)₅), and 2-propenyltrimethylsilane (allyltrimethylsilane) (ATMeSi), magnetic black fibrous material composed of amorphous ultrafine particles were produced under irradiation with intense Nd:YAG laser light at 355 nm. Chemical structures were studied from FT-IR and Raman spectra. It was shown that Co(CO)3NO and Fe(CO)5 molecules evolved terminal C≡O groups, and Co and Fe atoms were connected via bridging C=O groups. ATMeSi also coordinated to Co atoms via C=C double bond of allyl group. The chemical compositions and the morphology of the magnetic particles were analyzed by scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS) and HRTEM images. Small amorphous particles with sizes of less than 50 nm joined together to form fibers, and crystalline spheres similar to the structure of Co_0.7Fe_0.3 were involved in some particles. Magnetization of the ultrafine particles was measured with a SQUID magnetometer. Magnetic susceptibility, χ, of the ultrafine particles was evaluated to be ∼2X10^-2 emu/g, and temperature dependence of χ supported the ferromagnetic behaviors of the particles. Under a magnetic field of 1-5 T, super-paramagnetic ultrafine particles were also produced in addition to ferromagnetic particles. Existence of several kinds of crystalline spheres was responsible to magnetic properties of the ultrafine particles.

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We have investigated the effects of electrons and ions on the discoloration of PCI using VI-Au and VI-Pt indicators as the probe to detect these actions visually. The actions of the electron and ion in DC plasma were distinguished by VI-Pt. The discoloration action to VI-Au by the action of the electron in rf plasma was similar to the discoloration action by a heat reaction. In addition, the effects of electrons and ions on the discoloration of PCI are slight when it is applied in the radio frequency plasma of 13.56 MHz.

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We demonstrated the efficacy of using a simple experimental approach, involving UV absorption spectroscopy, to monitor the transport of reactive oxygen and nitrogen species (RONS) through an agarose film (as surrogate for real tissue) into deionized (DI) water. The experiment involved placing a 4 mm thick agarose film over a quartz cuvette filled with DI water. The agarose film was exposed to a non-thermal, He atmospheric-pressure plasma jet (APPJ) and the UV absorption of the DI water was recorded in real-time. Our results indicate an accumulation of RONS within the agarose film during APPJ exposure and a subsequent time-lapsed release of RONS into the DI water. Curve fitting of the UV spectra suggested the APPJ transported and / or generated at least four RONS (NaNO₂, HNO₃, H₂O₂ and O₂) through the 4 mm thick agarose film. Our approach of analyzing the delivery depth of RONS through synthetic tissue targets might find use in the future development of APPJ medical therapies and for improving our understanding of APPJ interactions with soft tissue.

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Both atmospheric and low-pressure plasma irradiation to seeds is effective for the growth enhancement of radish sprouts. On the other hand, there is no relation between the UV light and the growth enhancement of radish sprouts. In excimer UV irradiation, oxygen atoms and ozone are generated by excimer UV light wavelength of 172 nm and 222 nm. But in plasma irradiation, ions O⁺, O₂⁺, oxygen atoms O(¹D), O(³P) and excited oxygen molecules ¹Σ_g⁺ are produced. The ions are not excluded from factor of growth enhancement because of its short life. From this difference, the growth enhancement is due to reactive oxygen species generated by plasma irradiation.

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In this study, methacrylic acid (MAA) was grafted onto a poly(tetrafluoroethylene) (PTFE) plate by the oxygen plasma treatment and subsequent photografting. The surfaces of the grafted PTFE plates prepared at shorter plasma treatment times and/or at lower monomer concentrations were modified hydrophilic at lower grafted amounts. Water absorptivity of the grafted layer increased with the grafted amount and the grafted layers formed at lower monomer concentrations possessed higher water absorptivity. For grafted PTFE plates prepared at the monomer concentration of 1.5 and 2.0 M after the plasma treatment, the substrate breaking occurred. The grafted amount at substrate breaking decreased with a decrease in the plasma treatment time, indicating that the location of photografting was restricted to the outer surface region at shorter plasma treatment times. It was made clear that the combination of the oxygen plasma treatment with the photografting of MAA was an effective procedure to modify the PTFE surface.

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In this study, the surface of a titanium substrate was nitrided by successive exposure to carbon felt atmospheric pressure microwave plasma (CAMP) using a frequency of 2.45 GHz, an output power of 1000 W and an irradiation time of 120 s. The oxynitrided titanium substrate thus obtained was immersed in simulated body fluid at 36.5 °C for 120 hours to assess in vitro bioactivity, following which a crystal-like material was found to have covered the oxynitrided surface. X-ray photoelectron spectroscopy and X-ray diffraction revealed that the material was hydroxyapatite generated from the SBF, indicating that the surface of the oxynitrided titanium substrate was in vitro biocompatible.

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Utilization of atmospheric pressure plasma jet (AP plasma jet) was investigated for polymerization of methyl methacrylate (MMA) through the radical generation method. The AP plasma jet has a character of high-energy field at a relatively low temperature. Furthermore, this procedure can supply various types of energies to extremely restricted region of target materials irrespective of the shape and topography of the surfaces. In a liquid phase polymerization, the formation of polymethyl methacrylate (PMMA) was recovered by adding the reaction solution to an poor solvent, methanol. The amount of recovered PMMA was linearly increased with the AP plasma jet irradiation time and the formation rate of PMMA of 1.1 mg min^-1 was obtained. From an infrared spectrophotometric analysis, no significant change was observed between the PMMA sample formed by AP plasma jet irradiation and a reference PMMA film. It is considered that the AP plasma jet contributes to trigger for radical polymerization without imparting any considerable damage on the polymer. In addition, the polymerization of MMA was also investigated in the vapor phase. A small amount of PMMA was generated on the target glass plate surface by the irradiation of AP plasma jet through the vapor phase containing MMA. This result suggests a possibility for construction of a new formation system of a polymer film.

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B₂H₆/He plasma and B₂H₆/H₂/He plasma treatments of PTFE were performed. Concentration of the B₂H₆ was varied through this experiment. Then defluorination degree and adhesive strength were measured. While B₂H₆ and hydrogen were effective for defluorination of PTFE surface, oxygen functional groups generated by post-oxidation improved adhesive strength. The atmospheric pressure glow plasma treatment with lower diborane concentration more modifies PTFE surface.

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The purpose of this study is to improve the durability and bone-compatibility of DLC films for use in dental implants. We fabricated ta-C:H films on Ti plates by CA method using a graphite solid and a CH₄ gas as a source for the DLC film, and investigated the CH₄ gas flow ratio dependence of the current?voltage characteristics, film properties, and film structures during the ta-C:H formation. It was found that an increase in production of CH_x ions leads to a decrease in the space impedance of the plasma with increasing CH4 gas flow, and to an increased substrate bias current. The ta-C:H films avoided hardness lowering and maintained the hardness of 48 GPa even for hydrogen content of 15.9 at.%. The ta-C:H film fabricated by the CA method was found to be much harder than the a-C:H film fabricated by the CVD method. Therefore, we can expect that ta-C:H films will exhibit good durability and improve the surface of the bone/dental implant. ID/IG ratio measured by Raman spectroscopy tended to decrease with increasing substrate bias voltage.

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We synthesized the polymer film immobilizing Au nano particles by the use of a durable hydrophilic surface fabricated by the plasma-assisted method. Two kinds of methods were used to immobilize Au nano particles. The LDPE-VEMAC-AU film (method B) could immobilize larger amount of Au nano particles than LDPE-AET-Au film. It was also shown that the oxidation of benzyl alcohol proceeded in basic aqueous solution with LDPE-VEMAC-AU film.

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The present study developed a new method of modifying the surface of polytetrafluoroethylene (PTFE) to increase its wettability, using low-temperature radio frequency (RF) plasma, thus lowering its contact angle and improving associated mechanical properties such as peel strength. We succeeded in generating a super hydrophilic PTFE surface with a contact angle of less than 4° using a low-temperature RF plasma generated from an argon, ammonia and water vapor mixture. During treatment, fluorine elimination was observed and hydrophilic functional groups containing oxygen and nitrogen atoms were found to bond to the PTFE surface. Simultaneously, the surface morphology was dramatically changed to obtain an effective level of roughness.

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