Papers - Noda, Kei

CH₃NH₃PbI₃ deposited on rubrene/pentacene bilayer by two-step method and its photovoltaic performance

Ikumi Kamikawa, Tetsuhiko Miyadera, Kohei Yamamoto, Yuji Yoshida, Takurou N Murakami, Kei Noda

JAPANESE JOURNAL OF APPLIED PHYSICS 63   12SP08-1 - 12SP08-4 2024.12

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted

• Access to Document (DOI)

CVD Grown Sub 10 nm Size g‑C₃N₄ Particle-Decorated TiO₂ Nanotube Array Composites for Enhanced Photocatalytic H₂ Production

Kosei Ito, Sho Yoneyama, Shusuke Yoneyama, Paul Fons, Kei Noda

ACS Materials Au (American Chemical Society)  5 ( 2 ) 299 - 307 2024.12

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted

• Access to Document (DOI)

Gas phase CO₂ photoreduction behaviors over composites of galvanostatically pulse-deposited Cu₂O nanoparticles and anodized TiO₂ nanotube arrays

Hayato Goto, Kosei Ito, Shivaji B. Sadale, Kei Noda

Advanced Engineering Materials (Wiley-VCH GmbH)  26 ( 23 ) 202302249-1 - 202302249-11 2024.11

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted

• Access to Document (DOI)

Nanoscale visualization of fast carrier dynamics in organic thin-film transistors by time-resolved electrostatic force microscopy

Yuji Yamagishi, Kei Kobayashi, Tomoharu Kimura, Kei Noda, Hirofumi Yamada

Journal of Applied Physics (AIP Publishing)  135   125501-1 - 125501-7 2024.03

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted

• Access to Document (DOI)

Controlling growth of lead halide perovskites on organic semiconductor buffer layers

Ikumi Kamikawa, Kohei Yamamoto, Tetsuhiko Miyadera, Yuji Yoshida, Takurou N Murakami, Kei Noda

JAPANESE JOURNAL OF APPLIED PHYSICS 63 ( 3 ) 03SP86-1 - 03SP86-4 2024.03

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted

• Access to Document (DOI)

Highly efficient hydrogen production and selective CO₂ reduction by C₃N₅ photocatalyst using only visible light

Kosei Ito, Kei Noda

Physical Chemistry Chemical Physics (Royal Society of Chemistry)  26 ( 1 ) 153 - 160 2024.01

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted

• Access to Document (DOI)

Cross-Plane Thermal Transport in Acceptor-Doped Thiophene-Based Polymer Thin Films Investigated by the 3-Omega Method

Takayama K., Ito G., Kanazawa S., Ikkatai R., Noda K.

Physica Status Solidi (A) Applications and Materials Science (Wiley)  220 ( 24 ) 2300110 2023.05

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted,  ISSN  18626300

　View Summary

Thermal transport properties in acceptor-doped thiophene-based polymer films such as poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) are investigated using the cross-plane 3-omega method. A bilayer structure consisting of polymer semiconductors sequentially doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) and poly(methylmethacrylate) (PMMA) on a Si substrate is originally prepared by spin coating and employed to prevent leakage current from a heater wire during the 3-omega measurements. Nondoped PBTTT thin film reveals an intrinsic cross-plane thermal conductivity of 0.49 W m−1 K−1, which is higher than that for nondoped P3HT film (0.20 W m−1 K−1). X-ray diffraction (XRD) analysis suggests that higher crystallinity of PBTTT films may result in higher thermal conductivity. The intrinsic thermal conductivity of P3HT and the interfacial thermal resistance between PMMA and P3HT are slightly increased at a low doping concentration (0.01 mg mL−1) and decreased at a higher doping concentration of 0.1 mg mL−1, whereas F4TCNQ doping reduces these values monotonously in the case of PBTTT layers. Furthermore, excess doping occurs only for P3HT and increments both intrinsic thermal conductivity and thermal resistance at PMMA/P3HT interface. The observed trend in the cross-plane thermal transport caused by the sequential doping can be attributed to the differences between P3HT and PBTTT in their crystallinity and effective doping levels.

• Access to Document (DOI)

Visible light-assisted hydrogen generation over platinum-loaded tungsten trioxide nanorods with the hexagonal and triclinic phases

Kosei Ito , Ryota Uchida , Kei Noda

Journal of Photochemistry & Photobiology, A: Chemistry (Elsevier)  443   114824-1 - 114824-9 2023.05

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted,  ISSN  10106030

　View Summary

Visible light-assisted hydrogen (H2) generation was attempted for tungsten trioxide (WO3) nanorods (NRs) loaded with platinum (Pt). WO3 NRs were synthesized with a simple hydrothermal method using sodium tungstate as a precursor and oxalic acid as a structure-directing reagent. A variety of structural analyses clarify that both the end parts of a single hexagonal WO3 NR are transformed into triclinic WO3 when oxalic acid is added during the NR synthesis. The WO3 NR synthesized without oxalic acid (WO3(0)) displayed site-selective photodeposition of Pt cocatalysts on the (1 0 0) plane, whereas the Pt photodeposition occurred preferentially at the end (triclinic) parts of the WO3 NR synthesized with 0.05 M of oxalic acid (WO3(0.05)). These site-selective Pt deposition allows us to consider an inversion of the redox reaction field in WO3(0) and WO3(0.05) sample. Pt-loaded WO3(0.05) showed better photocatalytic activity ascertained in both methylene blue decomposition and H2 generation from water and methanol mixture, which can be brought about by a direct Z-scheme formed at heterojunctions between hexagonal and triclinic WO3 in a single NR. Finally, photoassisted H2 generation from water including ammonia borane with Pt-loaded WO3(0.05) was demonstrated, where a H2 generation rate under visible light irradiation was about 2.7 times higher than that in the dark. This result suggests a new strategy of efficient H2 generation based on synergetic effects of the WO3 NR photocatalysis and the Pt catalysis.

• Access to Document (DOI)

Intricate behaviors of gas phase CO₂ photoreduction in high vacuum using Cu₂O-loaded TiO₂ nanotube arrays

Hayato Goto, Hikaru Masegi, Shivaji B. Sadale, Kei Noda

Journal of CO2 Utilization (Elsevier)  59   101964-1 - 101964-11 2022.03

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted

　View Summary

Photoreduction of carbon dioxide (CO2) in gas phase was investigated over composites of Cu2O nanoparticles (CNPs) and anodized TiO2 nanotube arrays (TNAs). CNPs with an average size of 90 nm were pulse-electrodeposited on vertically aligned hollow TiO2 nanotubes having average pore size of 90 nm. Radical trapping experiments with electron spin resonance spectroscopy suggest that photoinduced charge separation occurs via direct Z-scheme mechanism in Cu2O-loaded TNA (CNP/TNA) sample. Successively, CO2 photoreduction for CNP/TNA from water/CO2 mixture was monitored using a quadrupole mass analyzer in high vacuum, where the partial pressures of intermediate and final reaction species were measured in real time under ultraviolet-visible (UV–VIS) light irradiation (300–600 nm). The photoreduction of CO2 on CNP/TNA happens through preferred generation of formaldehyde (HCHO) and methanol (CH3OH), while platinum-loaded TNA (Pt/TNA) produced methane (CH4) and hydrogen (H2) instead of HCHO and CH3OH. Carbon monoxide (CO) formation was commonly observed for both CNP/TNA and Pt/TNA specimens. These results reveal that CO2 photoreduction occurs through hydrogenation in gas phase over CNP/TNA even in high vacuum, although CO2 deoxygenation to CH4 is conventionally dominant for gas phase reactions.

• Access to Document (DOI)

Characteristic control of n-channel organic thin-film transistors using a dimethyl-substituted benzimidazole dopant

Kei Noda, Yuki Hiruma, Yuji Yoshihashi, Masashi Uebe, Akihiro Ito

ACS Applied Electronic Materials (ACS Publications)  3 ( 12 ) 5296 - 5306 2021.12

Research paper (scientific journal), Joint Work, Accepted

　View Summary

4-(N,N-Dimethylamino)phenyl-substituted 1,3-dimethyl-2,3-dihydro-1H-benzimidazole (N-DMBI-H) has been utilized as a solution-processable n-type dopant in organic electronics. In this study, a dimethyl-substituted N-DMBI-H derivative (DMe-N-DMBI-H), in which two methyl groups are attached at the terminal 5- and 6-positions of the benzimidazole moiety of N-DMBI-H molecule, has been examined to control its electron-donating ability. The effectiveness of DMe-N-DMBI-H as a solution-processable donor dopant has been clarified by evaluating electrical characteristics of DMe-N-DMBI-H-doped PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) thin-film transistors, such as field-effect mobility, gate threshold voltage, and contact resistance. Our electrochemical and electrical characterizations as well as quantum chemical calculations have suggested that DMe-N-DMBI-H works as a donor dopant somewhat stronger than N-DMBI-H.

• Access to Document (DOI)

Effect of deposition potential and annealing on performance of electrodeposited copper oxide thin films for supercapacitor application

Shivaji B. Sadale, Sushant B. Patil, Aviraj M. Teli, Hikaru Masegi, Kei Noda

Solid State Sciences (Elsevier)  123   106780-1 - 106780-10 2021.11

Research paper (scientific journal), Joint Work, Accepted,  ISSN  12932558

　View Summary

The present investigation describes the effect of deposition potential and annealing on copper oxide (CuO) thin film as a supercapacitor electrode. CuO thin films were grown on conducting glass substrate (ITO) by electrodeposition at room temperature and annealed for 3 hrs. at 300° C. The formation of polycrystalline CuO was confirmed by X-ray diffraction (XRD) & X-ray photoelectron spectroscopy (XPS). Significant change in morphology of CuO thin films after annealing has been observed. Annealing has improved crystallinity, surface coverage and grain connectivity of CuO thin films. CuO thin films deposited at −450 mV vs. Ag/AgCl exhibits essential porosity for electrochemical reactions. Higher deposition potential of −500 mV vs. Ag/AgCl leads to formation of compact CuO thin films. Electrochemical performance of as deposited and annealed CuO thin films were compared using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 1 M aqueous KOH electrolyte. The maximum specific capacitance of 57.44 F/g at 20 mV/s was measured. The CuO thin film shows specific energy of 2.67 Wh/kg with a coulombic efficiency of 77.27 % at 0.5 mA/cm2 current density. These results showed that the electrodes prepared by simple, low-cost electrodeposition method can be promising electrode materials for supercapacitor application.

• Access to Document (DOI)

Visible light responsive photocatalytic hydrogen production over composites of anodized TiO₂ nanotube array and graphitic carbon nitride measured with a gas circulating reactor

Hikaru Masegi, Naoyuki Doi, Sho Yoneyama, and Kei Noda

JAPANESE JOURNAL OF APPLIED PHYSICS (Japanese Journal of Applied Physics)  60 ( 10 ) 105504-1 - 105504-8 2021.09

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00214922

　View Summary

Gas phase photocatalysis over composites of electrochemically anodized titania nanotube (TNT) arrays and graphitic carbon nitride (g-C3N4) nanoparticles were examined with a home-made, gas-circulating reactor system. g-C3N4 nanoparticles were deposited onto anodized TNT surfaces by facile thermal polymerization using melamine and urea as precursors. The existence of g-C3N4 on TNT arrays clearly improved hydrogen production from gas phase photocatalytic decomposition of water/methanol mixture under visible light (VIS) irradiation (370-800 nm). The enhanced production of hydroxyl radicals via water photooxidation for TNT/g-C3N4 composites was also ascertained by photoluminescence measurement using terephthalic acid as a radical trap. These results deriving from synergetic effects of TNT and g-C3N4 can be attributed to the photogenerated hole-electron separation enhanced at TNT/g-C3N4 interface, suggesting that g-C3N4 is a metal-free sensitizer for enabling VIS responsive photocatalysis in anodized TNTs even for gas phase reactions.

• Access to Document (DOI)

Real-time monitoring of photocatalytic methanol decomposition over Cu₂O-loaded TiO₂ nanotube arrays in high vacuum

Hikaru Masegi, Hayato Goto, Shivaji B. Sadale, and Kei Noda

Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena 38 ( 5 ) 052401-1 - 052401-10 2020.09

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

All-electrochemical fabrication of α-Fe₂O₃ nanotube array/Cu₂O composites toward visible-light-responsive photocatalysis

Hikaru Masegi, Sakiko Imai, Shivaji B. Sadale, and Kei Noda

JAPANESE JOURNAL OF APPLIED PHYSICS 59 ( 6 ) 065503-1 - 065503-7 2020.06

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Solvent vapor annealing for poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b] thiophene) thin films toward transistor fabrication

Mark Yi-Hsuan Chiang, Tomohiro Kinoshita, and Kei Noda

JAPANESE JOURNAL OF APPLIED PHYSICS 59 ( SD ) SDDA02-1 - SDDA02-8 2019.12

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Density measurement for carbon nanotube film grown on flat substrates

Kazuhiko Omote, Raita Hirose, Naoya Imayama, Kei Noda, Ryo Endoh, Naoyuki Sugiyama

APPLIED PHYSICS EXPRESS 13 ( 1 ) 016501-1 - 016501-5 2019.12

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Spin-filter effect by introducing an edge vacancy on armchair graphene nanoribbons with oxygen termination

Katsuya Yabusaki, Kenji Sasaoka, Kei Noda and Yuji Awano

JAPANESE JOURNAL OF APPLIED PHYSICS 58 ( 4 ) 045001-1 - 045001-4 2019.03

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Effects of an edge vacancy on electron transport in zigzag-graphene nanoribbons with oxygen terminations

Katsuya Yabusaki, Kenji Sasaoka, Kengo Takashima, Kei Noda and Yuji Awano

JAPANESE JOURNAL OF APPLIED PHYSICS 58 ( 2 ) 025002-1 - 025002-4 2019.01

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Temperature dependence of photoinduced hydrogen production and simultaneous separation in TiO₂ nanotubes/palladium bilayer membrane

Junki Asai, Kei Noda

Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena 36 ( 4 ) 04H101-1 - 04H101-7 2018.07

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

A dendritic oligoarylamine-substituted benzimidazole derivative as a useful n-type dopant

Masashi Uebe, Yuji Yoshihashi, Kei Noda, Masayuki Matsubara, Akihiro Ito

Journal of Materials Chemistry C 6 ( 24 ) 6429 - 6439 2018.06

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Local carrier dynamics in organic thin film transistors investigated by time-resolved Kelvin probe force microscopy

Yuji Yamagishi, Kei Kobayashi, Tomoharu Kimura, Kei Noda, Hirofumi Yamada

Organic Electronics 57 ( 9 ) 118 - 122 2018.06

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Contact effects analyzed by a parameter extraction method based on a single bottom-gate/top-contact organic transistor

Shunsuke Takagaki, Hirofumi Yamada, Kei Noda

JAPANESE JOURNAL OF APPLIED PHYSICS 57 ( 3S2 ) 03EH04-1 - 03EH04-6 2018.03

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Photocatalytic decomposition of gaseous methanol over anodized iron oxide nanotube arrays in high vacuum

Takahiro Ohta, Hikaru Masegi, Kei Noda

Materials Research Bulletin 99   367 - 376 2018.03

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Experimental and numerical investigation of contact doping effects in dinaphthothienothiphene thin-film transistors

R. Yamamoto, K. Noda, Y. Wada, T. Toyabe

Electronics and Communications in Japan 100 ( 12 ) 61 - 68 2017.10

Research paper (scientific journal), Joint Work

• Access to Document (DOI)

Experimental and Numerical Investigation of Contact Doping Effects in Dinaphthothienothiophene Thin-Film Transistors

Ryo Yamamoto、Kei Noda、Yasuo Wada、Toru Toyabe

IEEJ Transactions on Electronics, Information and Systems 137 ( 1 ) 20 - 25 2017.01

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Device Simulation Analysis of Contact Modification in Organic Thin-Film Transistors

NODA KEI

IEICE Technical Report 116 ( 281 ) 1 - 4 2016.10

Research paper (conference, symposium, etc.), Joint Work,  ISSN  0913-5685

DC Hall-effect measurement for inkjet-deposited films of poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) by using microscale gap electrodes

Shinri Ozaki, Yasuo Wada, Kei Noda

SYNTHETIC METALS 215   28 - 34 2016.05

Research paper (scientific journal), Joint Work,  ISSN  0379-6779

• Access to Document (DOI)

Visualization of trapped charges being ejected from organic thin-film transistor channels by Kelvin-probe force microscopy during gate voltage sweeps

Yuji Yamagishi, Kei Kobayashi, Kei Noda, Hirofumi Yamada

APPLIED PHYSICS LETTERS 108 ( 9 ) 093302-1 - 093302-5 2016.03

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Extraction of contact resistance and channel parameters from the electrical characteristics of a single bottom-gate/top-contact organic transistor

Shunsuke Takagaki, Hirofumi Yamada, Kei Noda

JAPANESE JOURNAL OF APPLIED PHYSICS 55 ( 3S2 ) 03DC07-1 - 03DC07-6 2016.02

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

All electrochemical fabrication of a bilayer membrane composed of nanotubular photocatalyst and palladium toward high-purity hydrogen production

Masashi Hattori, Kei Noda

APPLIED SURFACE SCIENCE 357 ( Part A ) 214 - 220 2015.12

Research paper (scientific journal), Joint Work

• Access to Document (DOI)

Experimental and numerical investigation on contact-area-limited doping for top-contact pentacene thin-film transistors with Schottky contact

Kei Noda, Yasuo Wada, Toru Toyabe

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 17   26535 - 26540 2015.10

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Surface potential measurement of fullerene derivative/copper phthalocyanine on indium tin oxide electrode by Kelvin probe force microscopy

Nobuo Satoh, Michio Yamaki, Kei Noda, Shigetaka Katori, Kei Kobayashi, Kazumi Matsushige, Hirofumi Yamada

JAPANESE JOURNAL OF APPLIED PHYSICS 54 ( 8S1 ) 08KF06-1 - 08KF06-6 2015.07

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Interlayer resistance and edge-Specific charging in layered molecular crystals revealed by Kelvin-probe force microscopy

Yuji Yamagishi, Kei Noda, Kei Kobayashi, Hirofumi Yamada

JOURNAL OF PHYSICAL CHEMISTRY C 119 ( 6 ) 3006 - 3011 2015.02

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Experimental and numerical analysis of channel-length-dependent electrical properties in bottom-gate, bottom-contact organic thin-film transistors with Schottky contact

Kei Noda, Yasuo Wada, Toru Toyabe

ORGANIC ELECTRONICS 15 ( 12 ) 3681 - 3687 2014.12

Research paper (scientific journal), Joint Work, Accepted

• Access to Document (DOI)

Intrinsic difference in Schottky barrier effect for device configuration of organic thin-film transistors

Kei Noda, Yasuo Wada, Toru Toyabe

ORGANIC ELECTRONICS 15 ( 7 ) 1571 - 1578 2014.07

Research paper (scientific journal), Accepted

• Access to Document (DOI)

Numerical investigation of organic thin-film transistors using a thermionic field emission model

Kei Noda, Yasuo Wada, Toru Toyabe

JAPANESE JOURNAL OF APPLIED PHYSICS 53 ( 6S ) 06JH02-1 - 06JH02-5 2014.05

Research paper (scientific journal), Accepted

• Access to Document (DOI)

Current Enhancement with Contact-Area-Limited Doping for Bottom-Gate, Bottom-Contact Organic Thin-Film Transistors

Kei Noda, Yusuke Wakatsuki, Yuji Yamagishi, Yasuo Wada, Toru Toyabe, Kazumi Matsushige

JAPANESE JOURNAL OF APPLIED PHYSICS 52 ( 2 ) 021602-1 - 021602-6 2013.02

Research paper (scientific journal),  ISSN  0021-4922

• Access to Document (DOI)

Investigation of electrical transport in anodized single TiO2 nanotubes

Masashi Hattori, Kei Noda, Tatsuya Nishi, Kei Kobayashi, Hirofumi Yamada, Kazumi Matsushige

APPLIED PHYSICS LETTERS 102 ( 4 ) 043105-1 - 043105-4 2013.01

Research paper (scientific journal),  ISSN  0003-6951

• Access to Document (DOI)

Organic field-effect transistors with molecularly doped polymer gate buffer layer

Yamagishi, Yuji, Noda, Kei, Yamada, Hirofumi, Matsushige, Kazumi

SYNTHETIC METALS 162 ( 21-22 ) 1887 - 1893 2012.12

Research paper (scientific journal),  ISSN  0379-6779

• Access to Document (DOI)

Donor-Acceptor Alternating Copolymer Based on Thermally Converted Isothianaphthene Dimer and Thiazolothiazole Subunits

Umeyama, Tomokazu, Hirose, Kohei, Noda, Kei, Matsushige, Kazumi, Shishido, Tetsuya, Saarenpaa, Hanna, Tkachenko, Nikoiai V., Lemmetyinen, Helge, Ono, Noboru, Imahori, Hiroshi

JOURNAL OF PHYSICAL CHEMISTRY C 116 ( 33 ) 17414 - 17423 2012.08

Research paper (scientific journal),  ISSN  1932-7447

• Access to Document (DOI)

Preparation and Photophysical and Photoelectrochemical Properties of a Covalently Fixed Porphyrin-Chemically Converted Graphene Composite

Umeyama, Tomokazu, Mihara, Junya, Tezuka, Noriyasu, Matano, Yoshihiro, Stranius, Kati, Chukharev, Vladimir, Tkachenko, Nikolai V., Lemmetyinen, Helge, Noda, Kei, Matsushige, Kazumi, Shishido, Tetsuya, Liu, Zheng, Hirose-Takai, Kaori, Suenaga, Kazu, Imahori, Hiroshi

CHEMISTRY-A EUROPEAN JOURNAL 18 ( 14 ) 4250 - 4257 2012.04

Research paper (scientific journal),  ISSN  0947-6539

• Access to Document (DOI)

Real-time investigation on photocatalytic oxidation of gaseous methanol with nanocrystalline WO3-TiO2 composite films

Sadale, Shivaji B., Noda, Kei, Kobayashi, Kei, Yamada, Hirofumi, Matsushige, Kazumi

THIN SOLID FILMS 520 ( 10 ) 3847 - 3851 2012.03

Research paper (scientific journal),  ISSN  0040-6090

• Access to Document (DOI)

A Photoconductive, Thiophene-Fullerene Double-Cable Polymer, Nanorod Device

Imahori, Hiroshi, Kitaura, Shinji, Kira, Aiko, Hayashi, Hironobu, Nishi, Masayuki, Hirao, Kazuyuki, Isoda, Seiji, Tsujimoto, Masahiko, Takano, Mikio, Zhe, Zhang, Miyato, Yuji, Noda, Kei, Matsushige, Kazumi, Stranius, Kati, Tkachenko, Nikolai V., Lemmetyinen, Helge, Qin, Lidong, Hurst, Sarah J., Mirkin, Chad A.

JOURNAL OF PHYSICAL CHEMISTRY LETTERS 3 ( 4 ) 478 - 481 2012.02

Research paper (scientific journal),  ISSN  1948-7185

• Access to Document (DOI)

Thermal Conversion of Precursor Polymer to Low Bandgap Conjugated Polymer Containing Isothianaphthene Dimer Subunits

Umeyama, Tomokazu, Hirose, Kohei, Noda, Kei, Matsushige, Kazumi, Shishido, Tetsuya, Hayashi, Hironobu, Matano, Yoshihiro, Ono, Noboru, Imahori, Hiroshi

JOURNAL OF PHYSICAL CHEMISTRY C 116 ( 1 ) 1256 - 1264 2012.01

Research paper (scientific journal),  ISSN  1932-7447

• Access to Document (DOI)

Hall-effect Measurement of Organic Semiconductor Layers Using Micro-scale Electrode Chips

Noda Kei, Matsushige Kazumi, Sugawara Akira, Wada Yasuo, Watahiki Tsutomu, Kiyosu Takahiro

IEEJ Transactions on Electronics, Information and Systems 132 ( 9 ) 1398 - 1401 2012

ISSN  0385-4221

　View Summary

<p>A new micro-electrode structure for Hall-effect measurements of organic semiconductor layers was proposed. The equations for the Hall-effect measurements based on the van der Pauw method indicate that narrower electrode gaps can decrease the resistance between contact points and enable Hall-effect measurement even for higher resistance materials such as organic semiconductors. According to this “scaling rule”, we fabricated a new electrode chip which consists of four small finger electrodes with a gap of micrometer-scale between diagonally opposite electrodes. In order to demonstrate the validity of this concept, Hall-effect measurements for FeCl₃-doped poly(3,4-ethylenedioxythiophene) (PEDOT) was performed using this new electrode structure, revealing that a 10-µm-gap electrode chip is effective for evaluating carrier concentration of down to around 10¹⁹ cm^-3. These Hall electrode chips are quite useful for quantitative analysis of carrier concentration and ca rier mobility in organic semiconductor materials.</p>

• Access to Document (DOI)

High-purity hydrogen generation by ultraviolet illumination with the membrane composed of titanium dioxide nanotube array and Pd layer

Hattori, Masashi, Noda, Kei, Matsushige, Kazumi

APPLIED PHYSICS LETTERS 99 ( 12 ) 123107-1 - 123107-3 2011.09

Research paper (scientific journal),  ISSN  0003-6951

• Access to Document (DOI)

Molecular doping effect in bottom-gate, bottom-contact pentacene thin-film transistors

Wakatsuki, Yusuke, Noda, Kei, Wada, Yasuo, Toyabe, Toru, Matsushige, Kazumi

JOURNAL OF APPLIED PHYSICS 110 ( 5 ) 054505-1 - 054505-6 2011.09

Research paper (scientific journal), Joint Work,  ISSN  0021-8979

• Access to Document (DOI)

Intricate photocatalytic decomposition behavior of gaseous methanol with nanocrystalline tungsten trioxide films in high vacuum

Sadale, Shivaji B., Noda, Kei, Kobayashi, Kei, Matsushige, Kazumi

APPLIED SURFACE SCIENCE 257 ( 23 ) 10300 - 10305 2011.09

Research paper (scientific journal),  ISSN  0169-4332

• Access to Document (DOI)

Comparison of Electrochemical Impedance Spectroscopy between Illumination and Dark Conditions

Adachi, Motonari, Noda, Kei, Tanino, Ryo, Adachi, Jun, Tsuchiya, Katsumi, Mori, Yasushige, Uchida, Fumio

CHEMISTRY LETTERS 40 ( 8 ) 890 - 892 2011.08

Research paper (scientific journal),  ISSN  0366-7022

• Access to Document (DOI)

Investigation of electron trapping behavior in n-channel organic thin-film transistors with ultrathin polymer passivation on SiO2 gate insulator

Tanida, Shinji, Noda, Kei, Kawabata, Hiroshi, Matsushige, Kazumi

SYNTHETIC METALS 160 ( 13-14 ) 1574 - 1578 2010.07

Research paper (scientific journal),  ISSN  0379-6779

• Access to Document (DOI)

Ultrathin polymer gate buffer layer for air-stable, low-voltage, n-channel organic thin-film transistors

Tanida, Shinji, Noda, Kei, Kawabata, Hiroshi, Matsushige, Kazumi

POLYMERS FOR ADVANCED TECHNOLOGIES 21 ( 7 ) 528 - 532 2010.07

Research paper (scientific journal),  ISSN  1042-7147

• Access to Document (DOI)

Hydrogen production from gas phase photocatalytic decomposition of methanol using Pt-supported nanocrystalline WO3 films

Shivaji B. Sadale, Kei Noda, Kei Kobayashi, Kazumi Matsushige

Physica Status Solidi C 8   552 - 554 2010.05

Research paper (international conference proceedings), Accepted

Gas phase photocatalytic decomposition of alcohols with titanium dioxide nanotube arrays in high vacuum

Masashi Hattori, Kei Noda, Kei Kobayashi, Kazumi Matsushige

Physica Status Solidi C 8   549 - 551 2010.05

Research paper (international conference proceedings), Accepted

N-channel operation of pentacene thin-film transistors with ultrathin polymer gate buffer layer

Noda, Kei, Tanida, Shinji, Kawabata, Hiroshi, Matsushige, Kazumi

SYNTHETIC METALS 160 ( 1-2 ) 83 - 87 2010.01

Research paper (scientific journal),  ISSN  0379-6779

• Access to Document (DOI)

Organosilane self-assembled multilayer formation based on activation of methyl-terminated surface with reactive oxygen species generated by vacuum ultra-violet excitation of atmospheric oxygen molecules

Kim, Young-Jong, Han, Jiwon, Sano, Hikaru, Lee, Kyung-Hwang, Noda, Kei, Ichii, Takashi, Murase, Kuniaki, Matsushige, Kazumi, Sugimura, Hiroyuki

APPLIED SURFACE SCIENCE 256 ( 5 ) 1507 - 1513 2009.12

Research paper (scientific journal),  ISSN  0169-4332

• Access to Document (DOI)

N-channel thin-film transistors based on 1,4,5,8-naphthalene tetracarboxylic dianhydride with ultrathin polymer gate buffer layer

Tanida, Shinji, Noda, Kei, Kawabata, Hiroshi, Matsushige, Kazumi

THIN SOLID FILMS 518 ( 2 ) 571 - 574 2009.11

Research paper (scientific journal),  ISSN  0040-6090

• Access to Document (DOI)

Alkyl and Alkoxyl Monolayers Directly Attached to Silicon: Chemical Durability in Aqueous Solutions

Sano, Hikaru, Maeda, Hajime, Ichii, Takashi, Murase, Kuniaki, Noda, Kei, Matsushige, Kazumi, Sugimura, Hiroyuki

LANGMUIR 25 ( 10 ) 5516 - 5525 2009.05

Research paper (scientific journal),  ISSN  0743-7463

• Access to Document (DOI)

Photocatalytic hydrogen production from gas-phase methanol and water with nanocrystalline TiO₂ thin films in high vacuum

Noda Kei, Hattori Masashi, Amari Kouichi, Kobayashi Kei, Horiuchi Toshihisa, Matsushige Kazumi

Materials Research Society Symposium Proceedings 1056   7 - 12 2008

　View Summary

<p>Photocatalytic hydrogen production with gas-phase reactions in high vacuum was examined for nanocrystalline anatase-type titanium dioxide (TiO₂) thin films. The hydrogen generation process on platinized TiC₂ specimens was investigated using a quadrupole mass spectrometer at a real-time scale under various partial pressures of gaseous methanol and water. As a result, hydrogen generation was successfully detected under ultraviolet (UV) ray illumination even in high vacuum (-10^-7 Torr). And the amount of produced H₂ largely depends on the temperature of TiO₂ samples, probably due to different surface states of TiO₂. This study suggests the possibility of new high-speed H₂ production system with gas-phase photocatalytic reactions.</p>

Flexible programmable logic gate using organic ferroelectric multilayer

Horie, Satoshi, Noda, Kei, Yamada, Hirofumi, Matsushige, Kazumi, Ishida, Kenji, Kuwajima, Shuichiro

APPLIED PHYSICS LETTERS 91 ( 19 ) 193506-1 - 193506-3 2007.11

Research paper (scientific journal),  ISSN  0003-6951

• Access to Document (DOI)

Real-time detection of photocatalytic hydrogen production for platinized titanium dioxide thin films in high vacuum

Noda, Kei, Hattori, Masashi, Amari, Kouichi, Kobayashi, Kei, Horiuchi, Toshihisa, Matsushige, Kazurni

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS &amp; EXPRESS LETTERS 46 ( 29-32 ) L749 - L751 2007.08

Research paper (scientific journal),  ISSN  0021-4922

• Access to Document (DOI)

Self-assembly of metal-virus nanodumbbells

Balci, Sinan, Noda, Kei, Bittner, Alexander M., Kadri, Anan, Wege, Christina, Jeske, Holger, Kern, Klaus

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 46 ( 17 ) 3149 - 3151 2007

Research paper (scientific journal),  ISSN  1433-7851

• Access to Document (DOI)

Switching characteristics in the ferroelectric organic molecular memories

Uemura H., Horie S., Noda K., Kuwajima S., Ishida K., Horiuchi T., Matsushige K.

Nanotechnology Materials and Devices Conference, 2006 (NMDC 2006) IEEE 1   148 - 149 2006

　View Summary

<p>Organic molecular memories are expected to become one of the essential key devices in the next-generation flexible digital instruments, and in this paper a novel non-volatile organic memory will be introduced. It is shown that the polarization switching characteristics in the ferroelectric films of vinylidene fluoride (VDF) oligomer and P(VDF/TrFE) copolymer change with their structural factors such as crystallinity and chain length of the materials, and the switching time becomes shorter and shorter with increasing applied electric field and reaches in the order of nano-second. Moreover, the possibilities of the application of such thin organic ferroelectric films to an infrared image sensor as well as the creation of the ultra high-density molecular memory by utilizing recent scanning probe microscopy (SPM) technique will be discussed.</p>

• Access to Document (DOI)

Pyroelectricity of Ferroelectric Vinylidene Fluoride-Oligomer-Evaporated Thin Films

Noda Kei, Ishida Kenji, Horiuchi Toshihisa, Yamada Hirofumi, Matsushige Kazumi

Japanese Journal of Applied Physics, Part 2: Letters 42 ( 11 A )  2003.11

ISSN  0021-4922

　View Summary

<p>The pyroelectricity of ferroelectric vinylidene fluoride (VDF)-oligomer [CF₃(CH₂CF₂)₁₇I]-evaporated film was investigated utilizing a low-frequency sinusoidal heat source. A current profile appeared as the summation of a fundamental sine wave with a frequency of the temperature change and its harmonic responses. The pyroelectric coefficient (p) of the 600-nm-thick VDF oligomer film was estimated to be -68 μC/m²K at 37°C, whose absolute value is larger than those reported for ferroelectric polymers. Various characteristics such as a large |p|, a small dielectric constant and suitability for preparation of thinner films suggest that the VDF oligomer is a promising material for application in pyroelectric thin-film infrared detectors.</p>

Remanent polarization of evaporated films of vinylidene fluoride oligomers

Noda Kei, Ishida Kenji, Kubono Atsushi, Horiuchi Toshihisa, Yamada Hirofumi, Matsushige Kazumi

Journal of Applied Physics 93 ( 5 ) 2866 - 2870 2003.03

ISSN  0021-8979

　View Summary

<p>Remanent polarization of evaporated films of vinylidene fluoride was investigated. Hysteresis curves were also realized. The film was found to have an extremely high crystallinity, and the electric dipoles arrange almost perpendicular to the film surface. The obtained value of coercive field was attributed to the steric hindrance.</p>

• Access to Document (DOI)

Investigation of ferroelectric properties of vinylidene fluoride oligomer evaporated films

Noda K., Ishida K., Mochizuki K., Kubono A., Horiuchi T., Yamada H., Matsushige K.

Materials Research Society Symposium Proceedings 748   217 - 222 2003

　View Summary

<p>Structures and electrical properties of newly synthesized vinylidene fluoride (VDF) oligomer [CF₃(CH₂CF₂)₁₇I] films evaporated onto various substrates around liquid nitrogen temperature were investigated. As a result, the VDF oligomer films were mainly formed with ferroelectric phase (form I) crystals and the molecular chains were oriented parallel to the substrate surfaces regardless of both the kind of the substrates and the thickness of the VDF oligomer films. In addition to these properties, the VDF oligomer films showed polarization reversal due to 180° rotation of the polar VDF oligomer molecules according to the applied voltages. This ferroelectric behavior was verified by local poling and piezoresponse measurements with an atomic force microscope, and by measurements of D-E hysteresis curves.</p>

Molecular-scale non-contact AFM studies of ferroelectric organic thin films epitaxially grown on alkali halides

Fukuma T., Kobayashi K., Noda K., Ishida K., Horiuchi T., Yamada H., Matsushige K.

Surface Science 516 ( 1-2 ) 103 - 108 2002.09

ISSN  0039-6028

　View Summary

<p>Epitaxially grown vinylidene fluoride oligomer thin films formed on KCl(0 0 1) surfaces were investigated by ultrahigh vacuum non-contact AFM (UHV-NC-AFM). Molecularly resolved NC-AFM images of organic thin layers on insulating surfaces were successfully obtained for the first time, which revealed the epitaxial growth process on a molecular-scale. It was found that the first monolayer formed on KCl(0 0 1) surface was composed of characteristic honeycomb-like structures while the following upper molecular layers consist of molecular-scale stripe structures. In addition, NC-AFM images of the first monolayer suggest a strong electrostatic interaction between the molecule in the layer and the AFM probe tip.</p>

• Access to Document (DOI)

Molecular ferroelectricity of vinylidene fluoride oligomer investigated by atomic force microscopy

Noda Kei, Ishida Kenji, Kubono Atsushi, Horiuchi Toshihisa, Yamada Hirofumi, Matsushige Kazumi

Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 40 ( 6 B ) 4361 - 4364 2001.06

ISSN  0021-4922

　View Summary

<p>Nanometer-scale electrical properties of local ferroelectric domains formed in thin films of newly synthesized vinylidene fluoride (VDF) oligomer were investigated by atomic force microscopy (AFM). Local poling and observation of the piezoelectric response revealed that the polarized domains were reversibly formed and erased in a nanometer-thick film by applying dc or pulse voltages between the electrically conductive AFM tip and the bottom electrode. The formed domain size depends on the pulse poling conditions and increases when the magnitude and the duration of a pulse voltage are increased. A local domain with a diameter of 65 nm was successfully created. The results in this work are comparable to those of previous studies performed on ferroelectric polymer thin films, suggesting that this material is one of the promising candidates for ferroelectric applications such as high-density data storages, and for molecular controls of ferroelectric properties.</p>

Structures and ferroelectric natures of epitaxially grown vinylidene fluoride oligomer thin films

Noda Kei, Ishida Kenji, Kubono Atsushi, Horiuchi Toshihisa, Yamada Hirofumi, Matsushige Kazumi

Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 39 ( 11 ) 6358 - 6363 2000.11

ISSN  0021-4922

　View Summary

<p>Structural and electrical properties of newly synthesized vinylidene fluoride (VDF) oligomer thin film have been investigated. The FTIR spectrum showed that the epitaxially grown film on KBr(001) substrate consists of form I (β phase) crystals and their c axes (molecular axes) and b axes (polar axes) are arranged parallel to the KBr substrate. To make electrical measurements possible, this film was transferred onto a gold bottom electrode without causing any changes in the crystalline structures. By using a modified atomic force microscope, we succeeded in the formation of local polarized domains as well as the clear observation of piezoresponse hysteresis curves in this sample. The coercive field and piezoelectric coefficient (d₃₃) for the 37-nm-thick film were about 200 MV/m and -3 pm/V, respectively. It was suggested that the b axis in the as-grown film rotated from the parallel to the perpendicular direction to the film surface during the poling process. This study reveals the ferroelectric characteristics in the VDF oligomer thin films for the first time.</p>

Structural and electronic characterization of epitaxially-grown ferroelectric vinylidene fluoride oligomer thin films

Ishida K., Noda K., Kubono A., Horiuchi T., Yamada H., Matsushige K.

Materials Research Society Symposium Proceedings 600   101 - 106 2000

　View Summary

<p>The structural and electric properties of newly synthesized vinylidene fluoride (VDF) oligomer thin films evaporated on various substrate were investigated. The structural behavior of the VDF oligomer thin films strongly depended on the kinds of substrate and substrate temperature during film preparation. In particular, the VDF oligomers epitaxially grew on KBr(001), aligned their molecular chain along the 〈110〉 direction of substrate surface, and were similar to polar Form I-type crystals of poly(VDF). While, the thin films evaporated on NaCl(001), SiO₂/Si were non-polar Form II-type or mixture of both Form I- and Form II-type crystals with their molecular chain normal to the surface. These facts indicated that crystal field of substrate, based on van der Waals and electrostatic interactions, strongly influenced to ferroelectric phase transition of the VDF oligomer. In addition, we demonstrate the formation of the local polarized domains in the epitaxial crystals by applying electric pulses from a conducting AFM probe used as a positionable top-electrode, and confirm their piezoelectricity of the VDF oligomers for the first time.</p>

Structures of vinylidene fluoride oligomer thin films on alkali halide substrate

Noda Kei, Ishida Kenji, Horiuchi Toshihisa, Matsushige Kazumi, Kubono Atsushi

Journal of Applied Physics 86 ( 7 ) 3688 - 3693 1999.10

ISSN  0021-8979

　View Summary

<p>Structures and crystal transformation of the newly synthesized vinylidene fluoride (VDF) oligomer with large electric dipoles evaporated on KCl (001) at various substrate temperatures have been investigated by an energy dispersive-grazing incidence x-ray diffraction system, Fourier transform infrared spectroscopy, and atomic force microscope (AFM). It was revealed that the molecules grow epitaxially and are influenced greatly by forces of the crystal surface field in terms of van der Waals or electrostatic potentials, and found that the phase transformation from form II (α phase) to form I (β phase) is induced by raising the temperature of the substrate from 50 to 80°C, accompanying the alternation in the crystal axes on the substrate from the a axis of form II to the polar b axis of the form I crystal. This fact suggests that the molecular chain of VDF oligomers aligns their c axes along the 〈110〉 row of K⁺ or Cl^- with the aid of electrostatic interaction under enough thermal movement. Moreover, in the transformation process, a pair of "rod-like" crystals, suggesting ferroelectric activity, were observed by AFM.</p>

エネルギー分散型斜入射 X 線分光法によるエピ成長強誘電性有機薄膜の構造評価

石田 謙司、野田 啓、久保野 敦史、堀内 俊寿、山田 啓文、松重 和美

IEICE Technical Report 98 ( 27 ) 17 - 24 1998

Research paper (conference, symposium, etc.), Joint Work,  ISSN  0913-5685