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

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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

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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

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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

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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

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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

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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.

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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

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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

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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

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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

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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

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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

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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

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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

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