• 한국응용과학기술학회지
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• 제30권3호
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• pp.461-471
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• 2013

Use of low bandgap polymers is the most suitable way to harvest a broader spectrum of solar radiations for solar cells. But, still there is lack of most efficient low bandgap polymer. In order to solve this problem, we have synthesised a new low bandgap polymer and investigated its interaction with the ILs to enhance its conductivity. ILs may undergo almost unlimited structural variations; these structural variations have attracted extensive attention in polymer studies. In addition to this, UV-Vis spectroscopy, confocal Raman spectroscopy and FT-IR spectroscopy results have revealed that all studied ILs (tributylmethylammonium methyl sulfate [$N_{1444}$][$MeSO_4$] from ammonium family) and 1-methylimidazolium chloride ([MIM]Cl, and 1-butyl-3-methylimidazolium chloride [Bmim]Cl from imidazolium family) has potential to interact with polymer. Further, protic ILs shows enhanced conductivity than aprotic ILs with low bandgap polymer. This study provides the combined effect of low bandgap polymer and ILs that may generate many theoretical and experimental opportunities.

• Journal of Electrical Engineering and Technology
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• 제5권2호
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• pp.329-336
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• 2010

The paper describes the electrical and optical properties of underwater discharges in highly inhomogeneous electric fields caused by 1.2/50 ${\mu}s$ impulse voltages as functions of the polarity and amplitude of the applied voltage, and various water conductivities. The electric fields are formed by a point-to-plane electrode system. The formation of air bubbles is associated with a thermal process of the water located at the tip of the needle electrode, and streamer coronas can be initiated in the air bubbles and propagated through the test gap with stepped leaders. The fastest streamer channel experiences the final jump across the test gap. The negative streamer channels not only have more branches but are also more widely spread out than the positive streamer channels. The propagation velocity of the positive streamer is much faster than that of the negative one and, in fact, both these velocities are independent of the water conductivity; in addition the time-lag to breakdown is insensitive to water conductivity. The higher the water conductivity the larger the pre-breakdown energy, therefore, the ionic currents do not contribute to the initiation and propagation of the underwater discharges in the test conditions considered.

• 열처리공학회지
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• 제33권6호
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• pp.277-283
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• 2020

Cu-Co-Si based alloy has a strengthening mechanism for Co₂Si intermetallic compounds deposited on the copper matrix after aging treatment and the solution treatment has a key influence on the strength and electrical conductivity of the final products. In this paper, the Cu-1.6%Co-0.38%Si alloy was fixed at the time and the solution treatment temperature was set at a temperature in the range of 800 to 950℃, and the change in mechanical properties was observed by fixing the temperature at 950℃ and changing the time. The microstructure was observed using an electron microscope and an optical microscope, and the changes in hardness, electrical conductivity, and bending workability after aging treatment were investigated. When the solution treatment time is less than 20 seconds, the solution treatment is not sufficient and the formation of precipitates contributing to the increase in hardness decreases and the hardness decreases after the aging treatment, and in more than 50 seconds, the hardness decreases due to the coarsening of the grains and the bending workability got worse.

• 대한전기학회논문지
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• 제40권1호
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• pp.91-98
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• 1991

Electrical conductivity of poly (3-alkylthiophene) derivatives with substituted long alkyl chain such as poly (3-butylthiophene), poly (3-hexylthiophene), poly (3-octylthiophene), poly (3-decylthiophene), poly (3-dodecylthiophene), and poly (3-docosylthiophene) increases with increasing temperature. However, after attaining a maxiumum value, it decreases with further temperature increase. Hysteresis is also observed in the temperature dependence of conductivity and absorption spectra. The absorption spectra also changes rapidly at the phase transition. These phenomena are discussed in terms of the increase of the energy band gap in the liquid states due to the decrease of co-planarity of thiophene rings accompanied by remarkable conformation changes.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1598-1601
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• 2008

We describe the fabrication of transparent conducting single-walled carbon nanotubes (SWCNTs) film on flexible substrate following the conventional spin coating method. The fabricated film was post treated with diluted acid solution and its electrical and optical characterizations were performed. The electrical conductivity of SWCNTs film was enhanced and the film was found to be attached strongly with substrate after the post treatment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.492-492
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• 2014

On account of the good conductivity and optical properties, TCO is generally used in silicon heterojunction solar cell since the emitter material, hydrogenated amorphous silicon (a-Si:H), of the solar cell has low conductivity compare to the emitter of crystalline silicon solar cell. However, the work function mismatch between TCO layer and emitter leads to band-offset and interfere the injection of photo-generated carriers. In this study, work function engineering of TCO by oxygen reactive sputtering method was carried out to identify the trend of band-offset change. The open circuit voltage and short circuit current are noticeably changed by work function that effected from variation of oxygen ratio.

• 한국전기전자재료학회논문지
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• 제13권1호
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• pp.52-59
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• 2000

In order to develop the transparent anti-static film with higher than 80% transparency to visible light, organic conductive compounds, N-methyl phenazinium 7,7,8,8-tetracyanoquinonedimethane (TCNQ) com-plex salts was synthesized and bar-coated on the polythylene terephthalate (PET) film using polymer binders. The best surface properties were obtained when acrylic binder was used. A single layer of TCNQ made of a acrylic binder showed a surface resistance of 10\ulcorner $\Omega$/ , a conductivity of 10\ulcorner S/cm, and a transparency of 75%. An optical microscopic examination revealed that the binder was first solidi-fied on the surface of PET film over which the needle-shaped TCNQ crystals were grown. An acrylic polyol coating over the TCNQ layer improved the transparency to 87%, becuase the acrylic polyol covers the surface of TCNQ crystals to reduce the surface roughness. This conductive material has thermal stability at room temperature and 4$0^{\circ}C$ over 4,000 h.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.195-198
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• 1996

In conducting systems based on LB films, TCNQ derivatives have been extensively studied as electron acceptor molecules. We have investigated the optical, electrical, and magnetic properties of Viologen-(TCNQ￣)$_2$LB films. In UV/visible absorption measurements, we have observed TCNQ￣ peak at 380 nm and dimer peak at 620 nm. The electron spin resonance measurements infer that Viologen-(TCNQ￣)$_2$LB film exhibits anisotropic properly. In other words, the LB film shows angular dependence. Iodine doping affects the degree of charge transfer and the conductivity of the films. The UV/visible absorption spectra of the LB film doped with I$_2$show peaks at near 400~430 nm and there is no dimer absorption peak. The in-plane electrical conductivity of the undoped film is approximately 4.2$\times$10$^{-6}$ S/cm.

• Current Photovoltaic Research
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• 제5권4호
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• pp.109-112
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• 2017

Various wt. ratios of indium were doped to the poly(3,4-ethylenedioxythiophene)-poly(styreneswulfonate) (PEDOT:PSS) to enhance the conductivity and transmittance. The transmittance of the films increased with increasing the amount of indium. The field emission scanning electron microscope (FESEM) image of 2.54 wt. % of indium doped PEDOT:PSS film shows large number of aggregated indium particles. However, more than 2.54 wt. % of indium doped PEDOT:PSS films showed reduced aggregated indium particles. Moreover, 4.47 wt. % of indium doped PEDOT:PSS film showed no aggregated particles. The resistivity of pure PEDOT:PSS film showed $880k{\Omega}{\cdot}cm$. The resistivity of 1.03 wt. % indium doped film reduced approximately 26 times compared with pure PEDOT:PSS film. The resistivity of indium doped film further reduced with increasing the amount of indium, which showed approximately $0.55k{\Omega}{\cdot}cm$ for the PEDOT:PSS film doped 4.47 wt. % of indium.

• 한국결정성장학회지
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• 제22권2호
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• pp.84-91
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• 2012

Single and few-layer graphene nanosheets (GNs) have successfully synthesized by a modified Hummer's method followed by chemical reduction of exfoliated graphene oxide (GO) in the presence of hydrazine monohydrate. GO and GNs were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray diffractions (XRD), Raman spectroscopy, Transmission electron microscopy (TEM), Atomic force microscopy (AFM), Optical microscopy (OM) and by electrical conductivity measurements. The result showed that electrical conductivity of GNs was significantly improved, from $4.2{\times}10^{-4}$ S/m for GO to 12 S/m for GNs, possibly due to the removal of oxygen-containing functional group during chemical reduction. In addition, the $NO_2$ gas sensing characteristics of GNs are also discussed.