We have proposed reverse mode liquid crystal (LC) cells by using a polymer stabilized LC technology. A reactive mesogen was dissolved in the LC and was polymerized by UV light from an Hg lamp (313 nm) and a UV-LED (365 nm) light sources. LC materials with and without UV absorption at each wavelength were prepared and electro-optical properties of the reverse mode cell were measured. It was found that the electro-optical property strongly depended on the UV absorption of the LC. Next we mixed LCs with and without UV absorption to adjust the UV intensity profile in the bulk of the LC cell. We successfully reduced the driving voltage by changing the absorption coefficient of LC mixtures.

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Three kinds of polymeric composites consisting of monomeric pyridine-terminated photoreactive compound and polymerthacrylate with photoinactive benzoic acid side chain were prepared and their photoinduced reorientation behavior was investigated using linearly polarized (LP) UV light and thermally induced self-organization of the composite. Due to different structure of the photoreactive dopant, reorientation direction and its performance are different among the samples: The dopant containing methoxybiphenyl and pyridine ring connected with imine bond form no mesomorphism and slight axis-selective photoreaction in the composite while the isomer of the dopant, connected phenylpyridine and methoxybenzene via imine bond showed a nematic phase and exhibit axis selective photoreaction but no thermionduced amplification of anisotropy in the composite. On the other hand, the dopant consisting of pyridine and methoxybenzene connected via imine bond showed a nematic phase with low glass transition temperature by combining with the host polymer. The composite exhibit thermionduced morecluar reorientation behavior by LPUV exposure below room temperature and subsequently annealed at 120 ^oC.

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Ultra-small metal particles are attractive materials exhibiting unique physical and chemical properties. In this study, we have produced polymer composites of 1-nm sized bismuth particles using phenylazomethine dendrimer templates and linear polymers. The formation of the polymer film with bismuth particles was revealed by STEM measurements. The stability of the ultra-small bismuth particles was demonstrated by XPS measurements. Variations of the protecting polymers were also successfully obtained by using polystyrene and polythiophene.

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Although organic light-emitting diodes (OLEDs) with internal quantum efficiencies of approximately 100% have been demonstrated using phosphorescent or thermally activated delayed fluorescent (TADF) emitters, the lifetimes of OLEDs have seldom been discussed owing to the complicated degradation mechanism. To realize OLEDs for practical applications, it is essential to extend their lifetimes. In recent years, attempts to improve the stability of OLEDs have been increasingly reported. One approach is to prevent the decrease in brightness resulting from OLED operation, so-called improvement of the operational stability. Another approach is to prevent the decrease in light-emitting area caused by oxygen/moisture, so-called improvement of the air-stability. In this review, molecular design and device design to improve the stability of OLEDs are introduced.

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Organic light-emitting diodes (OLEDs) were prepared using the P1 polymer and then characterized. P1 was synthesized via the direct C-H/C-H cross coupling reaction between octafluorobiphenyl and bithiophene monomers. By analyzing the electroluminescence properties of various OLED structures, P1 was found to exhibit more favorable ambipolar transport, compared with F6T2, which consists of fluorene and bithiophene units. The octafluorobiphenyl monomer was already known to exhibit fewer undesired homocoupling defects in P1. Thus, our experimental results in this study proved that octafluorobiphenyl was useful not only for the cross coupling reaction but also for adding new functions to polymers.

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Herein, we demonstrated that alkyl ammonium salts containing the Br anion, oleylamine bromide (OAM-Br), was used as an interfacial engineering layer between the hole transport layer (HTL) and the perovskite QDs to passivate cation- and anion-defects in perovskite QDs. The OAM-Br interfacial layer enables a high PLQY due to the suppression of surface defects in perovskite QDs. Thus, the CsPbBr₃ QD-LEDs with an OAM-Br layer exhibited a maximum power efficiency of 3.35 lm/W and an external quantum efficiency (EQE) of 2.08% that which are higher efficiencies than those of the LEDs without an OAM-Br layer.

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Organic thin-film photovoltaic cells (OPV) consisting of poly(3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C₆₁-butyric-acid-methyl ester (PCBM) were deposited with our developed desktop spray coater, rCoater. Organic thin films were deposited using two different spray nozzles: a two-fluid spray nozzle and a rotary-atomizing spray nozzle. The deposition conditions were optimized and the photovoltaic (PV) characteristics were measured. OPVs deposited using the two-fluid spray nozzle under optimized conditions exhibited better PV performance than those deposited using a spin coat method. The organic thin films fabricated using the two-fluid spray had a stacked structure by many small disk-like grains.

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As newly designed electrochromic devices (ECDs), we fabricated a multi-patterned display (MPD) and a tube-shaped display (TSD) with Fe(II)-based metallo-supramolecular polymer (polyFe) and/or Ru(II)-based polymer (polyRu). The MPD was fabricated by staking three independent ECDs. The device thickness was less than 5 mm using both-sides-coated ITO glasses. The MPD presented eight different images with high contrast and fast response. The bleaching and coloring times (T_b and T_c) were 1.7 and 2.0 s at 500 nm, in which the absorption attributed to polyRu appears, respectively, and 3.6 and 1.8 s at 600 nm, in which the absorption attributed to polyFe appears, respectively. The TSD was successfully fabricated using two flexible ITO-PET films and two tube-shaped glasses. The TSD also showed good electrochromic behavior (T_b: 22 s and T_c: 3.6 s). These results guarantee the achievement of the further application for new design of architecture or appliance.

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We demonstrated electrochemical charge storage in a Layer-by-layer assembled hybrid film. A cationic polymer, which contain ruthenium complex (pCM/Ru) and negatively charged Prussian blue (PB) nanoparticles, were assembled onto an ITO electrode a using layer-by-layer technique, so that pCM/Ru layer located in an inner layer and PB located in an outer layer. The electrochemical property of the hybrid film was studied by cyclic voltammetry (CV) measurement. The first scan of CV cycle showed an asymmetric spectrum in which oxidation current was about 1.7 times larger than reduction current, whereas those current values were almost identical for 2^nd and 3^rd CV cycles. The asymmetric CV spectrum indicates that PB at the outer layer was catalytically oxidized by pCM/Ru layer and stored positive charges at the first CV cycle.

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An electroswitching device that enables modulation of both photoluminescence and coloration was obtained. The device consisted of luminescent lanthanide(III) complex Eu(hfa)₃(TPPO)₂ (photoluminescence material) and an diheptyl viologen HV²⁺ (electrochromic material). Coloration and emission control were achieved by only electrochemical reactions of HV²⁺. The coloration of the device was controlled by HV²⁺ electrochromism. Photoluminescence control was also achieved by the HV²⁺ electrochromism via intermolecular energy transfer from the excited states of Eu(III) ions to colored HV^+·. However, there were some problems that the response time of switching between emission and coloration was quite slow (approximately 15 minutes), and the representation stability of switching between emission and coloration was low. These problems would be caused by absence of counter electrode reaction material against HV²⁺ redox. In order to improve the response time of the cell and decrease the driving voltage for dual-mode representation, we introduced prussian blue (PB) modified electrode as an electrochromical counter redox material.

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High performance reflector is significant structure for efficiency improvement of organic and inorganic solid-state light emitting devices because a large difference in the refractive index between the light source and air leads to multiple internal reflections at the reflector. Then we focused on wide angular light incidence and designed a total internal omnidirectional reflector (TI-ODR) based on transparent oxide layers. The simulation results showed that light extraction structure with TI-ODR gives 17% and 4% efficiency enhancement compared to typical Ag based mirror for organic LED (n=1.8) and inorganic LED (n=2.4), respectively. Then the TI-ODR on blue LED structure was fabricated and that showed enhancement effect of about 8%. The layers are composed of conductive layer for current distribution, low-index thick layer for total internal reflection (TIR) of wide angular light, and high-index layer for the reinforcement of adhesion of layers.

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Surface properties of polymers such as wettability and adhesiveness play an important role in industrial applications. The properties can be enhanced by fabricating a mesoscopic structure to the surface. In this study, we examined a chemical etching which is a simple and direct technique for the surface profile control, using atomic hydrogen generated by hot-wire catalytic method. Several tens of nanoscale structures were fabricated on poly(methyl methacrylate) (PMMA) surface by atomic hydrogen irradiation, and the size and pitch of the structure could be controlled by reaction temperature and time. The wettability of PMMA film surface changed from hydrophilicity to hydrophobicity by formation of mesoscopic structures.

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Expanded-polytetrafluoroethylene (ePTFE) generally exhibits good compatibility with blood in the form of a vascular graft material; however, the small diameter grafts exhibit a low patency rate. ePTFE, with a diameter of less than 6 mm, is usually not used to perform a bypass surgery because of its high occlusion rate due to thrombosis or thick neointimal formation. Therefore, to improve the patency rate of ePTFE, coating the inner surface of ePTFE using Diamond-like Carbon (DLC), which exhibits outstanding biocompatibility, is investigated. However, in reality, medical applications for a long-sized tube that has a diameter of less than 6 mm with a DLC-coated inner wall are scarce. Hence, in this study, AC high-voltage methane plasma Chemical Vapor Deposition is employed to form the bio-compatibilized inner wall of a small-diameter long-sized medical tube, and a Hydrogenated Amorphous Carbon (a-C:H) deposition technique is developed. Further, methane plasma discharge is confirmed to be confined within the ePTFE vascular graft tube (inner diameter of 4 mm and an overall length of 150 mm) with the inner wall being successfully coated by the a-C:H film.

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In this study, we developed an elongated parallel plate type dielectric barrier discharge(DBD) device with pre-ionization electrodes for large-area surface modification of fluorine contained resin films, such as polytetrafluoroethylene (PTFE) and ethylene tetrafluoroethylene (ETFE). By optimizing a phase difference between pre-ionization and main discharge voltages, we confirmed that an intensified DBD plasma was generated between main electrodes having an electrode area of 50 × 200 mm² and a gap of 5 mm. Uniformity of surface modification of fluorine contained resin films treated by DBD plasmas were examined under air and helium circumstances using carboxyl-reactive fluorescence dye for different polymer materials (PTFE, ETFE and polyethylene) and treatment times.

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The morphology of polymer nano-film in organic solvents and water was studied by ¹H-NMR and atomic force microscope (AFM) measurement. ¹H-NMR spectra of polymer nano-film in CD₃OD suggested that the crosslinking and stearic acid moiety could freely move. It was also shown that the morphology of polymer nano-film in CDCl₃ might be cylindrical or spherical structure with stearic acid moiety as outer shell, and that in D₂O the stearic acid moiety might exist in the inner core. It was also indicated from AFM images that polymer nano-film kept a spread form in methanol and a particle-like shape in chloroform and water.

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Plasma sterilization methods have been studied for over 20 years in Japan and around the world, and are currently being developed for practical application. However, persisting challenges, such as the speed of the sterilization treatment, treatment of pathogenic proteins on medical equipment, and the compatibility of plasma with materials of medical equipments, currently limit the widespread application of the techniques. This paper introduces research into plasma sterilization for practical use, which is currently being carried out.

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Thick film resist is applied to a template for microelectrode used in semiconductor device integration. Utilization of positive type resist in chemically amplified system for thick film is expected to improve production efficiency of semiconductor device integration, but improvement of resolution is required. In order to improve the resolution of chemically amplified positive tone thick film resist, chemical structure of the dissolution inhibitor (DI) was designed for the control of solubility in resist polymer. The increase of molecular size in DI improved the dissolution inhibiting ability for the resist polymer in the unexposed area and the high acidity of the deprotected DI having carboxyl group improved dissolution promoting ability for the resist polymer in the exposed area. The resist containing DI possessing a large molecular size and high acidity improved its sensitivity and resolution.

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It is important to evaluate the particle removal force in surface cleaning techniques using physical action. In this study, we measured a lateral removal force of highly adhered polymer particles on a glass plate. The polymer particles were baked on a glass plate at different temperatures to control adhesion. The removal force was measured with a self-sensitive cantilever in open-air and underwater conditions. As a result, the removal forces in both air and water were almost identical, of the order of 10² μN. The adhesion forces of these particles were approximately 10³ times higher than particles sprinkled on the plate without baking. In addition, two types of force curves were obtained depending on the heating temperature and duration. At high and low heating temperatures, the force curve increased gradually, showing a clear maximum value and sharp decrease. The particles were removed when the force achieved its maximum. However, under the middle heating temperature and short duration, the force curve gradually increased and then gradually decreased. Several scanning times were needed to remove the particles. This result indicated that the particles gradually reduced their binding forces. It was found that duration is an important factor for particle removal, in addition to the force acting on the particles.

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Polyacrylic acid (PAA) aqueous solution was treated with O₃ microbubbles and O₃ water, there was no difference in decrease in molecular weight of PAA due to the presence or absence of microbubbles. Regardless of dissolved O₃ concentration, O₃ microbubbles alone did not cause reduction in TOC and mineralization did not proceed. In the advanced oxidation proses with hydrogen peroxide added, the molecular weight and TOC decreased. It is considered that active oxygen is generated from hydrogen peroxide by advanced oxidation and PAA is decomposed. From these results, it is no considered generation of reactive oxygen species by microbubbles in the decomposition of PAA.

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Resist stripping phenomenon with laser irradiation was observed by using a time-resolved analysis. The time change of the resist stripping phenomenon by a probe laser irradiation was observed from the viewpoint of the intensity change of the probe laser. As for the laser irradiation in the water, the probe laser intensity arrived at the maximum after around 40 μs. During the pump laser irradiation of 8 ns, a large compressive stress of -10 MPa was confirmed inside the resist from the FE analysis results. The generation of this compression stress is important for starting the resist stripping process, and is thought to improve the resist removal efficiency.

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Photoresist removal method using hydrogen radicals, which are produced on a tungsten hot-wire catalyst, is effective to resolve some environmental and industrial problems in conventional methods for the fabrication of electronic devices. However, its removal rate is not as good as that of the conventional ones. We have previously described that the removal rate of a positive-tone novolac photoresist is enhanced by the addition of a small amount of oxygen gas to the atmosphere, in which hydrogen radicals are produced. Oxidizing radicals, such as OH and O radicals, can be produced together with H radicals. In present study, we examined the effects of oxygen addition on base polymers of KrF and ArF photoresists: the former is poly(vinyl phenol) (PVP), and the latter is poly(methyl methacrylate) (PMMA). Effects of oxygen addition on PVP was confirmed, as was found for the novolac photoresist. On the other hand, the effects on PMMA were different from the cases of the novolac photoresist and PVP. Results were ascribed to the presence or absence of benzene rings, the properties of polymers and the reactivity of oxidizing radicals.

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Interest in microscale 3D lithography continues to grow with the development of new tools and new patterning materials. To date most available materials are rigid, glassy systems derived from stereolithography studies. Soft materials lack the same level of sophistication, but there is a drive to improve this situation with the introduction of new elastomers and hydrogels. A general strategy is lacking for these 3D patterning systems as there is for the production of chemically amplified photoresists. This paper describes both positive and negative tone chemically amplified 3D materials as well and photocured systems based on radical and cationic crosslinking systems.

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Additive manufacturing generally describes a process of producing macro scale 3D-objects by the addition (or formation) of one patterned layer, of the overall object, onto a subsequent layer. In this fashion the target structure is produced in a layer-by-layer process. Selective area atomic layer deposition (SA-ALD) is, fundamentally, an additive manufacturing process where the layer-by-layer process occurs at the atomic level. A patterned surface is generated by exploiting disparate surface chemistries where a metal oxide is deposited in a targeted area. One method of enabling this process is through the use of organic monolayers that can form from a collection of well organized small molecules onto one surface and not another. These self-assembled monolayers (SAMs) can act as effective barriers to block the deposition of up to hundreds of thermal ALD cycles or can be used in combination with repair strategies to extend selective deposition capabilities. Recent efforts have focused on increasing the durability of these monolayer blocking layers. To this end we have designed SAM components that contain an aligning hydrogen bonding component that aid in directing the formation of well aligned monolayers as well as acting as a supramolecular cross-link. Furthermore, the components contain a photoactive diyne moiety that can be subsequently polymerized after irradiation to produce a robust ALD barrier. On structured surfaces this photoactive SAM achieved better deactivation properties than commercially available materials providing access to materials that produce a robust barrier in shorter formation times and withstand a great number of ALD cycles.

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A polyimide porous membrane was fabricated using a relatively simple novel process. The process involves making a coating from a polyamic acid solution in which silica fine particles were dispersed, baking it for imidization, etching it with HF for silica removal, and controlling pore size with alkaline solution. In order to construct a porous structure, removal of silica fine particles by HF and control of pore diameter by an alkali solution were effective. Surface and cross section observation of the porous membrane by SEM and pore size measurement by a perm-porometer revealed that the membrane had a three-dimensional homogeneous microporous structure. Thermal analysis and organic solvent immersion testing confirmed the high heat resistance and chemical resistance of the porous membrane. The unique features revealed in this testing suggest that this porous membrane has various potential applications.

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Evanescent-wave-based nano-stereolithography, which uses the ultra-thin field distribution of evanescent wave to solidify photosensitive resin, provides a sub-micrometer vertical resolution of each layer. In fabrication process, cured resin (solid state) is submerged in uncured resin (liquid state). The interfaces between the cured and the uncured resin are made up of half-cured resin in a state of the uncompleted polymerization. Due to the gradient boundary directly determines the thickness of each fabrication layer and greatly influences the quality of products, it is of great significance to study the gradient boundary in the fabrication process. We proposed in-process measurement of gradient boundary using the reflection interference technique to monitor the formation of cured resin and investigate the gradient boundary. In this method, the variation of refractive index of resin in curing process has been utilized in the measurement. Measurement light was deduced near the critical angle to obtain a susceptible total internal reflection condition. In the verification experiment, a compact experiment system including fabrication and measurement sections has been developed. Two beams of light in the different wavelength have been delivered into the system as fabrication and measurement light, respectively. Resin exposed by increasing time has been measured by our proposed method at various incident angles near the critical angle. The refractive index distribution and the depth gradient boundary have been successfully measured. The results prove that the refractive index of cured resin is different in the position; the span of gradient is not constant as well. The maximum span of gradient boundary in center was measured in around 250 nm. This work that helps us clearly understand the curing process and the formation of the cured layer in EWNSL provides a research basis for further and detailed research in the nanoscale stereolithography.

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A conductive film and the micropattern were prepared by laser-induced reduction of graphene oxide (GO). A 532 nm laser beam was scanned on a film made from a GO disper-sion solution using a galvano-scanner system. The influences of the laser irradiation condi-tions such as laser power, scan speed, and atmosphere on the chemical structure changes of a reduced graphene oxide (rGO) were studied by micro-Raman spectroscopy. The Raman scattering intensities of D, G, and 2D bands were remarkably influenced by the laser irradiation conditions. The formation of a few-layer graphene plane structure was suggested by a low ratio of intensities of D/G bands (I_D/I_G) and the shape of 2D band in the Raman spectra. The surface resistivity was decreased with increasing in the laser power corresponding to the decrease of the I_D/I_G ratio in the laser-induced reduction under an inert gas (Ar) atmosphere. Conductive rGO micro-grid structures were fabricated by laser direct writing using a GO film in Ar.

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