• 분석과학
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• 제8권4호
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• pp.663-668
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• 1995

Ion transport of a polypyrrole/chloride (PPy/Cl) film and a polypyrrole/poly(styenesulfonate) (PPy/PSS) film as a function of applied dc potential was investigated by employing electrogravimetric impedance technique and electrochemical impedance technique. The cation and anion contribution to the whole charge capacitance and the diffusion coefficients of cation and anion in a PPy/PSS film were calculated by fitting the electrogravimetric impedance data with proposed model circuit. The diffusion coefficients of $Na^+$ in a 1 M $NaClO_4$ solution are over 1 order of magnitude larger than those of $ClO{_4}^-$, and $ClO{_4}^-$ contribution to charge compensation decreases as dc potential lowers. The charge compensation of a PPy/Cl film ir a 1 M CsCl solution is carried out largely by $Cl^-$ at 0.2 V vs. Ag/AgCl and by $Cs^+$ as well as $Cl^-$ at -0.4 V.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.54.1-54.1
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• 2012

Recent significant development of organic electronics is worthy of notice for its practical application as well as fundamental understandings. Complementary-like logic circuit is a key factor to realize actual operating organic electronic devices since its advantages of low power dissipation, good noise margin and stable operations. In this reason, studies on ambipolar properties of organic materials which can act as either n-type or p-type are getting more attentions. Performances of ambipolar transistors vary a lot along its molecular structures and film properties. When properly fabricated, balanced hole and electron mobilities over 1 cm2/Vs were observed recently. Study of charge transport in ambipolar organic transistors to understand this high performance was carried out through charge modulation spectroscopy.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.670-674
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• 2012

The photovoltaic performance of solid-state dye-sensitized solar cells employing hole transport material (HTM), 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9'-spirobifluorene (spiro-MeOTAD), has been investigated in terms of HTM overlayer thickness. Two important parameters, soak time and spin-coating rate, are varied to control the HTM thickness. Decrease in the period of loading the spiro-MeOTAD solution on $TiO_2$ layer (soak time) leads to decrease in the HTM overlayer thickness, whereas decrease in spin-coating rate increases the HTM overlayer thickness. Photocurrent density and fill factor increase with decreasing the overlayer thickness, whereas open-circuit voltage remains almost unchanged. The improved photocurrent density is mainly ascribed to the enhanced charge transport rate, associated with the improved charge collection efficiency. Among the studied HTM overlayer thicknesses, ca. 230 nm-thick HTM overlayer demonstrates best efficiency of 4.5% at AM 1.5G one sun light intensity.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1805-1808
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• 2006

In this paper, we describe a versatile use of fullerene(C60) as a charge transporting material for organic light-emitting diodes. The use of fullerene as a buffer layer for an anode, a doping material for hole transport layer, and an electron transport layer was investigated. Fullerene improved the hole injection from an anode to a hole transport layer by lowering the interfacial energy barrier and enhanced the lifetime of the device as a doping material for a hole transport layer. In addition, it was also effective as an electron transporting material to get low driving voltage in the device.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.171-174
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• 1995

Space charge formation in epoxy loaded with silica and calcium carbonate has been studied. The epoxy itself showed almost no charge at up to 40 kV/mm. The addition of fillers such as SiO$_2$and CaCO$_3$resulted in homocharge formation, which was attributed to the interfacial trapping of injected charge at epoxy/filler interfaces. The amount of charge showed a maximum at 20-40 parts per hundred resin above which the charge decreased gradually. This was tentatively attributed to the enhanced interconection of charge transport path by an increased filler content

• 한국방사선학회논문지
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• 제4권4호
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• pp.37-40
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• 2010

본 연구에서는 X선 조사에 의해 생성된 전하의 이동현상을 조사하기 위해 비행시간 측정방법을 이용하였다. 이 측정기술은 일반적으로 디지털 X선 영상 변환물질의 전하 트랩 및 수송현상에 유용한 방법이다. 비행시간 측정법을 이용하여 a-Se 광도전체의 전하 수송자의 과도시간 및 이동속도를 측정하였다. 시편제작을 위해 열증착법을 이용하여 유리기판위에 $400{\mu}m$ 두께의 a-Se 필름을 제작하였다. 측정결과, 전자와 정공의 과도시간은 $10V/{\mu}m$의 전기장에서 각각 $229.17{\mu}s$ 와 $8.73{\mu}s$ 였으며, 이동속도는 각각 $0.00174cm^2/V{\cdot}s$, $0.04584cm^2/V{\cdot}s$ 였다. 측정결과, 전자와 정공의 이동 속도의 측정값에 다소 큰 차이를 보였으며, 이 결과로부터 전하수송 및 트랩 기전을 분석하는데 이용하였다.

• Bulletin of the Korean Chemical Society
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• 제28권4호
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• pp.607-612
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• 2007

Relationship between charge transfer mechanism and quantum coherence has been investigated using a realtime quantum dynamics approach. In the on-the-fly filtered propagator functional path integral simulation, by separating paths that belong to different mechanisms and by integrating contributions of correspondingly sorted paths, it was possible to accurately obtain quantitative contribution of different transport mechanisms. For a 5'-GAGGG-3' DNA sequence, we analyze charge transfer processes quantitatively such that the governing mechanism alters from coherent to incoherent charge transfer with respect to the friction strength arising from dissipative environments. Although the short DNA sequence requires substantially strong dissipation for completely incoherent hopping transfer mechanism, even a weak system-environment interaction markedly destroys the coherence within the quantum mechanical system and the charge transfer dynamics becomes incoherent to some degree. Based on the forward-backward path deviation analysis, the coherence variation depending on the environment is investigated numerically.

• 한국막학회:학술대회논문집
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• 한국막학회 2008년도 춘계 총회 및 학술발표회
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• pp.3-3
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• 2008

• 한국진공학회:학술대회논문집
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• 한국진공학회 2006년도 제31회 학술논문발표회 초록집
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• pp.62-62
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• 2006

• 대한환경공학회지
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• 제37권11호
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• pp.649-655
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• 2015

본 연구에서는 막 기반 수처리 기술의 핵심인 막 성능 및 특성을 혁신적으로 개선시키기 위한 새로운 형태의 막으로서 그래핀과 세라믹을 결합하는 세라믹 기반 그래핀 막(Ceramic-based graphene membrane (CbGM))을 만들고, 막에서 일어나는 물질 이동 특성을 파악하였다. 수투과 및 염 제거의 역할을 하는 활성층으로서 그래핀이 사용되었으며, 간단한 Filtration-assisted assembly (FAA) 방법을 도입하여 막을 합성하였다. 합성한 막의 표면 형태 및 특성 분석을 위해 주사전자 현미경 및 접촉각을 분석하였으며, 막 성능 및 특성 파악을 위해 3가지 용질(i.e., NaCl, $MgCl_2$, $Na_2SO_4$)을 회분식 정삼투 시스템에서 용질 이동을 측정하였다. 표면 형태 특성 분석과 물질 이동 결과를 통해, 그래핀 층의 두께 보다는, 활성층을 구성하는 그래핀 조각들 사이의 교합(Interlocking)이 막에 선택성 부여함에 있어서 가장 중요함을 확인하였다. 또한, 농도차를 구동력으로 하는 막 공정에 CbGM을 적용하였을 때, 수중의 음이온과 양이온의 최외각 전하비($Z^-/Z^+$)값이 증가할수록 용질 이동이 비례적으로 촉진되었으므로, CbGM의 표면이 양으로 하전되어 있으며, 이것이 전하된 물질의 이동에 매우 큰 영향을 끼친다는 것을 확인하였다.