• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.380-381
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• 2007

This paper reports on the deposition conditions and properties of ITO films used as electrode layer in a organic light emitting diodes on a PET substrate. The deposition technique employed was specially designed roll-to-roll sputtering. The oxide was deposited at room temperature in an argon and oxygen plasma on a transparent conducting ITO layer on a PET film. The influence of deposition parameters such as DC power, working pressure and oxygen partial pressure has been investigated, in order to obtain the best compromise between a high deposition rate and adequate electro-optical properties. Electrical and optical properties of ITO films were analyzed by Hall measurement examinations with van der pauw geometry at room temperature and UV/Vis spectrometer analysis, respectively. In addition, the structural properties and surface smoothness were measured by x-ray diffraction and scaning electron microscopy, respectively. From optimized ITO films grown by roll-to-roll sputter system, good electrical$(6.44{\times}10^{-4}\;{\Omega}-cm)$ and optical(above 86 % at 550 nm) properties were obtained. Also, the ITO films exhibited amorphous structure and very flat surface beacause of low deposition temperature.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.75.2-75.2
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• 2013

Atomic layer deposition (ALD), utilizing self-limiting surface reactions, could offer promising perspectives for future efficient energy conversion devices. The capabilities of ALD for surface/interface modification and construction of novel architectures with sub-nanometer precision and exceptional conformality over high aspect ratio make it more valuable than any other deposition methods in nanoscale science and technology. In the context, a variety of researches on fabrication of active materials for energy conversion applications by ALD are emerging. Among those materials, one-dimensional nanotubular titanium dioxide, providing not only high specific surface area but also efficient carrier transport pathway, is a class of the most intensively explored materials for energy conversion systems, such as photovoltaic cells and photo/electrochemical devices. The monodisperse, stoichiometric, anatase, TiO2 nanotubes with smooth surface morphology and controlled wall thickness were fabricated via low-temperature template-directed ALD followed by subsequent annealing. The ALD-grown, anatase, TiO2 nanotubes in alumina template show unusual crystal growth behavior which allows to form remarkably large grains along axial direction over certain wall thickness. We also fabricated dye-sensitized solar cells (DSCs) introducing our anatase TiO2 nanotubes as photoanodes, and studied the effect of blocking layer, TiO2 thin films formed by ALD, on overall device efficiency. The photon convertsion efficiency ~7% were measured for our TiO2 nanotubebased DSCs with blocking layers, which is ~1% higher than ones without blocking layer. We also performed open circuit voltage decay measurement to estimate recombination rate in our cells, which is 3 times longer than conventional nanoparticulate photoanodes. The high efficiency of our ALD-grown, anatase, TiO2 nanotube-based DSCs may be attributed to both enhanced charge transport property of our TiO2 nanotubes photoanode and the suppression of recombination at the interface between transparent conducting electrode and iodine electrolytes by blocking layer.

• 공업화학
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• 제25권5호
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• pp.447-454
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• 2014

유기태양전지는 제조비용이 저렴하고 플렉서블 전자소자에 적용이 가능하다는 장점들로 인해 최근 많은 연구가 진행되고 있다. 일반적인 정구조의 태양전지(conventional structured solar cell)의 경우 10%대의 향상된 발전 효율을 보이고 있으나, 여전히 기타 Si 및 CIGS 등과 같은 태양전지에 비해 낮은 효율과 짧은 수명은 상용화의 걸림돌로 작용하고 있다. 일반적으로 유기태양전지의 짧은 수명은 유기물의 광산화뿐만 아니라 수분 및 산소에 의한 음극, 양극 소재의 부식으로 인한 소재/소자 열화 문제로 설명되어지고 있다. 한편 이와 같은 문제점을 해결하기 위해 새로운 소자 구조(역구조 태양 전지; Inverted structured solar cell)가 제안되었으며 전자 수송층 및 기능성 계면 소재 연구를 통한 발전 효율 및 수명 향상에 관한 연구가 꾸준히 되고 있다. 그 결과 최근 2D/3D 산화 아연(ZnO) 소재를 역구조 태양전지의 전자 수송층으로 적용하고 건,습식 표면 후처리를 통해 약 9% 수준의 발전효율을 달성하였다. 본 총설에서는 ZnO를 기반으로 하는 전자 수송층 소재의 연구 동향 및 역구조 태양전지의 효율 향상 기술에 관한 최신 연구 동향을 소개하고자 한다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.87-87
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• 2010

Photoelectrochemical (PEC) systems are promising methods of producing H2 gas using solar energy in an aqueous solution. The photoelectrochemical properties of numerous metal oxides have been studied. Among them, the PEC systems based on TiO2 have been extensively studied. However, the drawback of a PEC system with TiO2 is that only ultraviolet (UV) light can be absorbed because of its large band gap (3.2 - 3.4 eV). Two approaches have been introduced in order to use PEC cells in the visible light region. The first method includes doping impurities, such as nitrogen, into TiO2, and this technique has been extensively studied in an attempt to narrow the band gap. In comparison, research on the second method, which includes visible light water splitting in molecular photosystems, has been slow. Mallouk et al. recently developed electrochemical water-splitting cells using the Ru(II) complex as the visible light photosensitizer. the dye-sensitized PEC cell consisted of a dye-sensitized TiO2 layer, a Pt counter electrode, and an aqueous solution between them. Under a visible light (< 3 eV) illumination, only the dye molecule absorbed the light and became excited because TiO2 had the wide band gap. The light absorption of the dye was followed by the transfer of an electron from the excited state (S*) of the dye to the conduction band (CB) of TiO2 and its subsequent transfer to the transparent conducting oxide (TCO). The electrons moved through the wire to the Pt, where the water reduction (or H2 evolution) occurred. The oxidized dye molecules caused the water oxidation because their HOMO level was below the H2O/O2 level. Organic dyes have been developed as metal-free alternatives to the Ru(II) complexes because of their tunable optical and electronic properties and low-cost manufacturing. Recently, organic dye molecules containing multi-branched, multi-anchoring groups have received a great deal of interest. In this work, tri-branched tri-anchoring organic dyes (Dye 2) were designed and applied to visible light water-splitting cells based on dye-sensitized TiO2 electrodes. Dye 2 had a molecular structure containing one donor (D) and three acceptor (A) groups, and each ended with an anchoring functionality. In comparison, mono-anchoring dyes (Dye 1) were also synthesized. The PEC response of the Dye 2-sensitized TiO2 film was much better than the Dye 1-sensitized or unsensitized TiO2 films.

• 공업화학
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• 제17권6호
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• pp.644-647
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• 2006

Indium zinc oxide (IZO) 박막이 radio frequency reactive magnetron sputtering 방법을 이용하여 증착되었으며 여러 가지 공정변수 중에서 $O_{2}$ 농도와 증착 후에 열처리 온도를 선택하여 박막의 광학적, 전기적 그리고 구조적인 특성을 조사하였다. $O_{2}$ 농도가 증가할수록 IZO 박막의 증착속도는 감소하였고 저항도는 증가하였으며 투과도는 약간 증가하는 경향을 보였다. Atomic force microscopy 분석의 결과로부터, 순수한 아르곤에서 증착된 박막의 표면이 가장 거칠었고 $O_{2}$가 첨가된 조건에서 증착된 박막들은 덜 거칠었다. 순수한 아르곤의 조건에서 증착된 IZO 박막들을 각각 250, 350, 그리고 $450^{\circ}C$에서 열처리하였다. 투과도와 저항도는 순수한 아르곤 조건에서 증착된 시료에서 가장 낮게 나타났고 $250^{\circ}C$의 열처리 온도까지 낮은 저항도가 유지되었다. 박막의 표면은 높은 온도에서 열처리된 시료일수록 더 매끄러운 표면을 가졌다. X-ray diffraction 결과를 통해서 높은 온도에서 열처리된 시료일수록 박막의 결정화가 잘 이루어진 것을 알 수 있었다.