This paper presents 2-(hydroxyl) quinoline lithium (Liq) used as an n-type dopant to improve white hybrid organic light-emitting diode (WHOLEDs) performance. The Liq doped tris(8-hydroxyquinolinato) aluminum (Alq₃) layer possessed enhanced electron injection, efficient hole and electron balance in the emitting layer, as one of the most essential issues for device applications. This work investigates the optimum recipe (Liq concentration and thickness) of Alq₃:Liq n-type doped electron injection layer (EIL) for WHOLED devices by comparing the current density and efficiency results with conventional Alq₃/LiF technique. A blocking layer or interlayer is inserted between emitting layer and EIL to avoid excitons quenched. In this work suitable material and optimum thickness for blocking layer are studied, a white small-molecular organic light-emitting diode (SM-OLEDs) based on a 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBi) stamping transfer process is investigated. The proposed stamping transfer process can avoid the complexity of the vacuum deposition process.

We deposited thin films of thiophene/phenylene co-oligomers (TPCOs) onto poly(tetrafluoroethylene) (PTFE) layers that were friction-transferred on substrates. These films were composed of aligned molecules in such a way that their polarizations of emissions and absorbances were larger along the drawing direction than those perpendicular to that direction. Organic field-effect transistors (OFETs) fabricated with these films indicated large mobilities, when the drawing direction of PTFE was parallel to the channel length direction. The friction-transfer technique forms the TPCO films that indicate the anisotropic optical and electronic properties.

Step-edge vertical channel organic field-effect transistors (SVC-OFETs) with a very short channel have been fabricated by a novel selective electrospray deposition (SESD) method. We propose the SESD method for the fabrication of SVC-OFETs based on a 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) semiconductor layer formed by SESD. In the SESD method, an electric field is applied between the nozzle and selective patterned electrodes on a substrate. We demonstrated that the solution accumulates on the selected electrode pattern by controlling the voltage applied to the electrode.

Displacement current measurement (DCM) is widely used as a method for analyzing carrier behaviors of organic devices. Carrier behaviors are analyzed using transient currents. On the other hand, electric-field-induced optical second-harmonic generation (EFISHG) measurement is capable of directly probing carrier motions in organic devices, where the migration of electric field stemmed from carriers is measured. In this study, we employed the DCM and EFISHG measurements for analyzing interfacial carrier behaviors in Au/pentacene/polyimide (PI)/indium-tin-oxide (ITO) double layer organic devices, where interfacial accumulated charges and electric fields formed in the pentacene layer were explored.

We have investigated both the film thickness and surface potential of organic semiconductors deposited on two kinds of electrodes by the simultaneous observation with the dynamic force microscopy (DFM)/Kelvin-probe force microscope (KFM). To clarify the interfacial properties of organic semiconductor, we fabricated samples that imitated the organic light emitting diode (OLED) structure by depositing bis [N,N '-(1-naphthyl)-N,N '-phenyl] benzidine (α-NPD) and tris (8-hydroxyquinolinato) aluminum (Alq₃), respectively, on indium-tin-oxide (ITO) as anode and aluminum (Al) as cathode by the vacuum evaporation deposition using intersecting metal shadow masks. This deposition technique enables us to fabricate four different areas in the same substrate. The crossover area of the deposited thin films were measured by the DFM/KFM, the energy band diagrams were depicted and we considered that the charge behavior of the organic semiconductor depended on the material and the structure.

We fabricated organic field-effect transistors (OFETs) having a thin layer of molybdenum trioxide (MoO₃), a Lewis acid, and evaluated their electrical characteristics. The insertion of a thin MoO₃ layer reduces the on/off ratio but improves the apparent mobility of the charge carriers. To identify the dominant mechanism responsible for this effect, we characterized devices having a 69-nm-thick pentacene layer with a 1-nm-thick MoO₃ layer either between the gold source and the drain electrodes or only directly under these electrodes. The former device exhibited a low on/off ratio, whereas the latter device exhibited an on/off ratio comparable to those of conventional pentacene OFETs without a thin MoO₃ layer, suggesting that the formation of charge-transfer (CT) complexes immediately above the conduction channel is the critical mechanism. CT complexes at the pentacene/MoO₃ interface immediately above the conduction channel contribute to the formation of an effective channel for off-currents as well as drain currents. Moreover, we also attempted to improve the on/off ratio by using a cloth to rub the surface of a thin MoO₃ layer immediately above the conduction channel to create what we believe to be a profile with abrupt changes in height in the direction of the drain current conduction in OFETs. Consequently, it was found that such a rubbed MoO₃ layer had a surface with a scratched pattern, and the on/off ratio of the OFET was improved, indicating that controlling the CT complex formation by patterning a MoO₃ layer can reduce the off-current in OFETs having a pentacene/MoO₃ active layer.

The fabrication of a grating structure formed by a solid-state electrolyte layer on a dye-TiO₂ film by the nanoimprinting technique using a polydimethylsiloxane (PDMS) stamp and its application in photoelectric conversion devices are described. The PDMS grating pattern is imprinted from blu-ray disc recordable. A silver electrode was deposited on the patterned solid-state electrolyte layers. Surface plasmon resonance (SPR) excitation was observed in the fabricated solar cells by irradiation with white light. The photoelectric conversion properties were measured to study the effect of the two types of SPR excitations, i.e., the propagating surface plasmon on the Ag grating surface and the localized surface plasmon from the Au nanoparticles on TiO₂.

A portable biofuel cell with an anode modified with glucose oxidase/ferrocene and a cathode modified with bilirubin oxidase was fabricated on a flexible polyimide substrate. The anode and the cathode with an area of 3×10 mm² were separated with a gap of 1 mm. Solidified glucose biofuel units were prepared by solidifying 50–200 mM glucose aqueous solution containing 0.5–2.5% agarose. The influences of the biofuel volume and glucose concentrations on power generation were investigated. The maximum power density was almost independent on the agarose concentration, and it continuously decreased as time clasped possibly due to the consumption of glucose and/or release of the enzymes from the electrodes. The maximum power and power density were 0.32 μW and 1.08 μW/cm² at 0.17 V, respectively when the solidified hydrogel biofuel unit with a dimension of 13×24×4 mm³ containing the 100 mM glucose aqueous solution and 2.5 wt% agarose was used. The biofuel cell continued to deliver the power density over 0.5 μW/cm² for more than 1 h.

The novel ladder-shaped polydiacetylene with a terephthalamide linker in the molecular center, namely poly(TPh-bisDA) was synthesized by photo-polymerization. The characteristics of thin films of polymer were dependent upon a casting solvent, but no significant change of backbone conformation of the PDA was observed. Obtained film is expected to be applied to the semi-conducting materials for organic field effect transistors (OFET).

The combination of a halogen-free solvent 1,2,4-trimethylbenzene and unmodified fullerene potentially provides a way to develop environmentally-friendly and cost-effective solution-processed organic photocells. In this paper, the thermal annealing effect on the optical absorption spectra in poly(3-hexylthiophene):unmodified-C₆₀ composites with various compositions is reported. It is found that the onset temperature of the absorption spectrum change is higher in the composites with higher fullerene content. It is speculated that strong interaction between the polymer main chain and C₆₀ tends to suppress the reorientation of polymer main chains in a composite with high C₆₀ content.

We report a real time method to monitor the chemical reaction in microdroplets, which contain an organic dye, 5(6)-carboxynaphthofluorescein and a CdSe/ZnS quantum dot using fluorescence spectra. Especially, the relationship between the droplet size and the reaction rate of the two reagents was investigated by changing an injection speed.

The numerical dispersibility measurement system was fabricated based on optical transparency to objectively evaluate undetectable dispersibility by naked eyes. The small deference of dispersibility and the dispersibility behaviors were simultaneously elucidated by the system. The abundance of octadecyl groups was also discussed from the result of dispersibility behaviors. The objective numerical evaluation is needed for precise analysis of dispersibility with respect to graphene, graphene derivatives and graphene related materials.

Polyimide thin films were prepared by vapor-deposition polymerization. Naphthalene carboxylic dianhydride (NTCDA) was coevaporated with either diamino naphthalene (DAN) or diamino benzophenone (DAB). Coevaporation of dianhydride and diamines yielded thin films of polyamic acids. A polyimide thin film was obtained by annealing the codeposited film of NTCDA-DAB. On the other hand, the codeposited film of NTCDA-DAN was not imidized by annealing. In both cases, chemical structures of the products were not largely influenced by the molar ratio of depositing monomers if sufficient amount of diamine molecules are supplied in the coevaporation process.

We demonstrated a novel technique to fabricate nanosized structures on a Nafion membrane, using thermal nanoimprinting with a 5 × 5 μm² square pattern Si mold without any polymer damage. A 24 MPa thermal imprinting pressure was used for 10 min. We observed high aspect ratio (∼1:10) pillars on the surface after imprinting at 200°C. Finally, we used a novel quartz mold with a 200 nm resolution dot pattern.

A quartz-crystal-microbalance (QCM) and surface-plasmon-resonance (SPR) hybrid sensor was prepared, and the depositions of polymer electrolytes layer-by-layer (LbL) films were observed in situ. The estimated thicknesses obtained from the QCM method were different from those obtained from the SPR method. This was estimated to be caused by film swelling and water contained in the film.

The effects of the gate dielectrics on ambipolar transport in top-gate-type polymer light-emitting transistors with single-layer and bilayer gate dielectrics are investigated. Hole field-effect mobility is dependent on the dielectric constant of the gate dielectric onto the active layer. Hole transport of devices is affected by the dipolar disorder in the first gate dielectric layer on the active layer. Electron threshold voltage tends to decrease with increasing the total stacked gate capacitance.

A transmission ellipsometric method without an aperture was recently developed to characterize the electro-optic (EO) performance of EO polymers. The method permits much simpler optical setup compared to the reflection method, and allows easy performance of the incident angle dependence measurements using a conventional glass substrate and uncollimated beam. This paper shows the usefulness of this method for a simple and reliable evaluation of the EO coefficient both for organic and inorganic EO materials, as well as analysis for uniaxial anisotropic materials.

In this study, flexible organic solar cells (OSCs) employing a solution-processed hole-transporting layer (HTL) and low temperature annealing active layer have been fabricated. Vanadium oxide (V₂O₅), poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), V₂O₅/PEDOT:PSS or PEDOT:PSS/V₂O₅ is used as the HTL. Poly(3-hexythiophene) (P3HT):[6,6]-phenyl C61-butyric acid methyl ester (PCBM) is used as the active layer. HTL and active layer are all formed by a spin coating method on polyethylene terephthalate (PET) substrates. The OSC configuration has been optimized in the study to be PET/ITO/V₂O₅/PEDOT:PSS/P3HT:PCBM/LiF/Al. Based on a low annealing temperature of 90°C for P3HT:PCBM and parameters optimization of solution-processed V₂O₅/PEDOT:PSS, the OSC demonstrates a current density (JSC) and power conversion efficiency (PCE) of 6.08 mA/cm² and 1.57%, while an OSC without the HTL has PCE around 0.06%. The V₂O₅/PEDOT:PSS stacked HTL provides not only a stepwise hole-transporting energy diagram configuration but a smooth film surface for coating P3HT:PCBM active layer, which subsequently increases charge carrier transporting capability and extracts holes from the active layer to the anode.

To immobilize cytochrome c (cyt. c) on ITO electrode with keeping its direct electron transfer (DET) activity, 10-carboxydecylphosphonic acid (10-CDPA) self-assembled monolayer (SAM) film was formed on ITO electrode. After 100 times washing process with exchanging phosphate buffer saline solution in the cell to fresh one, in situ slab optical waveguide (SOWG) absorption spectral measurement proved that about 80% of cyt. c immobilized on 10-CDPA modified ITO electrode was adsorbed on ITO electrode. Additionally SOWG spectral change of cyt. c between oxidized and reduced forms was observed with setting the ITO electrode potential at 0.3 and -0.3 V vs. Ag/AgCl, respectively showing DET reaction between cyt. c and ITO electrode occurred. About 30% of a monolayer coverage was estimated from the coulomb amount in the surface area of oxidation and reduction peaks on cyclic voltammetry (CV) data. CV peak current maintained 84% for ITO electrode modified with 10-CDPA SAM film after 60 min continuous scan with 0.1 V/sec from 0.3 and -0.3 V vs. Ag/AgCl.

This paper presents a compact orthomode junction with low pass filters for high power applications. It consists of a circular waveguide step, a matching element for a high frequency band, and coupling sections straddle the circular waveguide step. These dimensions were optimized to achieve wideband performances and to support a high power rating. The structure without rectangular to circular transition is simple and comprised of two milled layers to divide E-plane of corrugated low pass filters. It can be easily manufactured and has low losses. The fabricated Ku/Ka-band orthomode junction was measured including power handling test of 2 kW at Ku-band. The measurement results demonstrated return loss of 21 dB and loss of 0.2 dB in the Ku- and Ka- band.

In the scattering problem of dielectric gratings in conical mounting, we have considered and formulated scattering fields using transverse electric (TE) and transverse magnetic (TM) waves. This paper formulates scattering fields by superpositions of right-circularly (RC) and left-circularly (LC) polarized waves through the matrix eigenvalue method.