著者

Horike Shohei Misaki Masahiro Koshiba Yasuko Morimoto Masahiro Saito Takeshi Ishida Kenji

出版者

Institute of Physics

雑誌

Appl. Phys. Express (ISSN:18820778)

巻号頁・発行日

vol.9, no.8, 2016-07-06

被引用文献数

9

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The tuning of the Seebeck coefficient of a single-walled carbon nanotube (SWCNT) film was achieved by using the dipole field of a ferroelectric polymer. The Seebeck coefficient was positive under an up-poling dipole field, but negative under a down-poling dipole field, whereas the control remained positive. This tunable behavior can be explained by selective carrier injection and accumulation, which was confirmed by the temperature dependence of electrical conductivity. Connecting p- and n-type SWCNT films tuned by dipole fields to create a π module resulted in a significant improvement in output voltage owing to the temperature difference between the two.

著者

Koshiba Yasuko Nishimoto Mihoko Misawa Asuka Misaki Masahiro Ishida Kenji

出版者

Institute of Physics

雑誌

Jpn. J. Appl. Phys. (ISSN:00214922)

巻号頁・発行日

vol.55, no.3, 2016-02-12

被引用文献数

4

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The thermal behavior of 1,2,4,5-tetracyanobenzene (TCNB), the synthesis of metal-2,3,9,10,16,17,23,24-octacyanophthalocyanine–metal [MPc(CN)<inf>8</inf>–M] (M = Cu, Fe, Ni) complexes by the tetramerization of TCNB, and the growth of MPc(CN)<inf>8</inf>–M nanorods were investigated. By chemical vapor deposition (CVD) in vacuum, MPc(CN)<inf>8</inf>molecules were synthesized and MPc(CN)<inf>8</inf>–M nanorods were formed on all substrates. Among them, CuPc(CN)<inf>8</inf>molecules were synthesized in high yield, and CuPc(CN)<inf>8</inf>–Cu nanorods were deposited uniformly and in high density, with diameters and lengths of 70–110 and 200–700 nm, respectively. The differences in the growth of MPc(CN)<inf>8</inf>–M nanorods were mainly attributed to the stability of the MPc(CN)<inf>8</inf>–M complex, the oxidation of ultrathin metal films, and the diffusion of metal atoms. Additionally, the tetramerization of TCNB by CVD at atmospheric pressure was performed on ultrathin Cu films, and the synthesis of CuPc(CN)<inf>8</inf>molecules was observed by in situ UV–vis spectroscopy. CVD under atmospheric pressure is also useful for the synthesis of CuPc(CN)<inf>8</inf>molecules.

著者

Inoue Takaaki Mori Akimitsu Koshiba Yasuko Misaki Masahiro Ishida Kenji

出版者

Institute of Physics

雑誌

Appl. Phys. Express (ISSN:18820778)

巻号頁・発行日

vol.8, no.11, 2015-10-14

被引用文献数

3

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The ferroelectric properties of perpendicularly oriented, highly crystalline vinylidene fluoride (VDF) oligomer thin films were investigated by using a planar device configuration consisting of comblike Cr–Au electrodes with a 1 µm gap. In-plane polarization switching was induced by the rotation of the VDF oligomer. As the measurement temperature was increased from 295 to 380 K, the coercive field (E<inf>c</inf>) decreased drastically from 124 to 7.7 MV/m. Furthermore, the thermal stability of our device significantly improved compared with that of conventional sandwiched devices utilizing VDF oligomer films with a parallel orientation.

著者

Kajihara Tadao Ueno Yoshikazu Tsujiura Yuichi Koshiba Yasuko Morimoto Masahiro Kanno Isaku Ishida Kenji

出版者

Institute of Physics

雑誌

Jpn. J. Appl. Phys. (ISSN:00214922)

巻号頁・発行日

vol.56, no.4, 2017-02-03

被引用文献数

8

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We investigated piezoelectric vibration energy harvesters with poly(vinylidene fluoride/trifluoroethylene) films and the improved power generation from using multistacked and stretched ferroelectric films on the cantilevers. The energy harvesters generated electric power with a resonant frequency of approximately 25 Hz, which corresponded to the ambient vibration. The power density of four-layered harvesters was estimated to be 2.5 µW/m³, which was larger than the power density of previous harvesters. The output power of stretched-film harvesters was 3.6 times the output obtained from unstretched films. In addition, because organic ferroelectric films are flexible, the resonant frequency of each harvester was practically constant even when using the techniques of multistacking and stretching.

著者

Horike Shohei Misaki Masahiro Koshiba Yasuko Saito Takeshi Ishida Kenji

出版者

Institute of Physics

雑誌

Jpn. J. Appl. Phys. (ISSN:00214922)

巻号頁・発行日

vol.55, no.3, 2015-12-18

被引用文献数

10

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We have investigated the thermoelectric power of single-wall carbon nanotubes (SWCNTs) with an ionic liquid (IL). The SWCNT/IL films showed simultaneous increase in electrical conductivity and the Seebeck coefficient compared with the pristine SWCNT. No thermoelectric power was observed for the IL. The X-ray diffraction pattern and impedance diagram showed a unique behavior with the concentration of IL, which implies that the interaction between the SWCNTs and IL enhances the thermoelectric power of the SWCNTs. As a result of the simultaneous increase in these parameters, the power factor exhibited a 10-fold increase.

著者

Morimoto Masahiro Koshiba Yasuko Misaki Masahiro Ishida Kenji

出版者

Institute of Physics

雑誌

Appl. Phys. Express (ISSN:18820778)

巻号頁・発行日

vol.8, no.10, 2015-10-01

被引用文献数

12

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We have investigated the temperature dependence of the piezoelectric coefficients and infrared sensor performance of spin-coated thin films of polyundecylurea (PUA11). The piezoelectric coefficients of the PUA11 films remained constant at temperatures above 180 °C and these films demonstrated thermal resistance superior to those of poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)] films. The infrared sensor performance of the PUA11 films was measured after annealing at 125 °C for 500 h and was found to have retained 84% of its preannealing level. The thermal stability of the PUA11 films was higher than that of the P(VDF/TrFE) films; moreover, PUA11 is also expected to have superior electrothermal stability.

著者

Morimoto Masahiro Koshiba Yasuko Misaki Masahiro Ishida Kenji

出版者

Institute of Physics

雑誌

Jpn. J. Appl. Phys. (ISSN:00214922)

巻号頁・発行日

vol.54, no.4, 2015-03-27

被引用文献数

8

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We have investigated the pyro- and piezoelectric properties of polyurea spin-coated films with thermal and chemical stability and their performance as infrared sensors. The piezoelectric coefficient d<inf>33</inf>was measured by a laser Doppler vibrometer to be 23.5 pC/N. This coefficient increased with the poling electric field up to around 75 MV/m, suggesting that the polyurea dipole is aligned by applying an electric field greater than 75 MV/m. When a triangular thermal wave was applied, a square-wave pyroelectric current was observed and the pyroelectric coefficient measured to be 5.11 µC/(m²·K). The infrared sensor performance of the polyurea thin film was examined by measuring the voltage sensitivity to infrared irradiation. The obtained result of 70.4 V/W at 1 Hz is consistent with the results calculated from the measured pyroelectric coefficient. Our findings suggest that the performance of the sensor may be improved by increasing the pyroelectric coefficient of the polyurea films.