• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.11
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• pp.36-43
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• 2008

In this parer aluminium-doped zinc oxide(ZnO:Al) conducting layer was deposited on polyethylene terephthalate(PET) substrate by r. f. magnetron sputtering method. The effects of gas pressure and r. f. sputtering power on the structural and electrical properties of ZnO:Al thin film were investigated experimentally. Especially the effect of position of PET substrate on the electrical properties of the film was studied and fixed to improve the electrical properties and also to increase the deposition rate. The results show that the structural and electrical properties of ZnO:Al thin film were strongly influenced by the gas pressure and sputtering power. The minimum resistivity of $1.1{\times}10^{-3}[{\Omega}-cm]$ was obtained at 5[mTorr] of gas pressure, and 18D[W] of sputtering power. The deposition rate of ZnO:Al film at 5[mTorr] of gas pressure was 248[nm/min]. and is higher by around 3 times compared to that at 25[mTorr].

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.632-637
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• 2015

Mesoporous $TiO_2$ granules were prepared by spray pyrolysis using nano-sized titania particles which were synthesized by a hydrothermal method, and they were evaluated as the photoanode of dye-sensitized solar cells. To enhance the cell efficiency, nanoparticles within granules were chemically interconnected by adding titanium ethoxide (TEOT) to colloidal spray solution. The resulting titania particles had anatase phase without forming rutile. $TiO_2$ granules obtained showed about 400 nm in size, the specific surface area of $74-77m^2/g$, and average pore size of 13-17 nm. The chemical modification of $TiO_2$ granules by adding TEOT initially to the colloidal spray solution was proved to be an effective way in terms of increasing both the light scattering within photoanode and the lifetimes of photo-excited electrons. Consequently, the light-harvesting efficiency of TEOT-modified granules (${\eta}=6.72%$) was enhanced about 14% higher than primitive nanoparticles.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.396-396
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• 2012

$TiO_2$ anatase nanotube arrays (NTAs) were grown by electrochemical anodization and followed annealing of Ti foil. Ethylene glycol/$NH_4F$-based organic electrolyte was used for electrolyte solution and using second anodization process to obtain free-standing NTAs. After obtaining NTAs, ITO film was deposited by sputtering process on bottom of NTAs. UV-curable NOA was used for attach free-standing NTAs on flexible plastic substrate (PEN). Solid state electrolyte (spiro-OMeTAD) was coated via spin-coating method on top of attached NTAs. Ag was deposited as a counter electrode. Under AM 1.5 simulated sunlight, optical characteristics of devices were investigated. In order to use flexible polymer substrate, processes have to be conducted at low temperature. In case of $TiO_2$ nano particles (NPs), however, crystallization of NPs at high temperature above $450^{\circ}C$ is required. Because NTAs were conducted high temperature annealing process before NTAs transfer to PEN, it is favorable for using PEN as flexible substrate. Fabricated flexible solid-state DSSCs make possible the preventing of liquid electrolyte corrosion and leakage, various application.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1509-1510
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• 2011

염료 감응형 태양전지 동작에 있어 상대전극 표면에서 전해질의 산화, 환원 반응이 일어나기 위한 촉매의 역할이 중요하며 그 중 Pt는 촉매로써 널리 쓰이는 물질이다. Pt 도포 방식은 sputtering, Pt paste를 이용한 doctor blade, Pt solution을 이용한 spin coating 등 여러 가지가 있으며 제작 조건에 따라 그 특성도 다르게 된다. 따라서 본 연구에서는 Pt solution의 열처리에서 온도를 달리하여 그에 따른 특성을 알아보자 하였다. 그 결과 Pt solution 소성온도가 $400^{\circ}C$일 때, 가장 적절한 Pt층이 형성되기 때문에 산화, 환원반응이 활발하게 되어 높은 효율(6.8%)의 DSC 특성을 얻을 수 있었다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1507-1508
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• 2011

본 논문에서는 전기장이 염료감응형 태양전지 광전극의 산화반도체($TiO_2$)에 미치는 영향에 대해 설명하고 DSC의 효율과 밀접한 관련이 있는 산화반도체의 결정구조 개선에 초점을 맞추어 효율을 향상시키고자 하였다. DSC의 광전극 제조에서 FTO 기판에 doctor-blade 방법을 통해 $TiO_2$ paste 도포 한 후 소성 직전 전기장을 인가하여 입자의 결정화를 돕는다. 이때 인가 전압과 전압을 인가하는 시간을 변화시키면서 실험하였다. 그 후 $450^{\circ}C$에서 30분 동안 소성하였다. FE-SEM으로 $TiO_2$의 형태를 보고 전기장이 $TiO_2$ 결정화에 미치는 영향을 확인하였고, current-voltage 특성 분석을 통해 에너지 변환 효율과 각 요소들을 비교하였다. UV-vis spectrophotometer, EIS 측정으로 각 DSC의 광 흡수율과 $TiO_2$/염료/전해질 영역에서의 저항을 분석하였다. 그 결과 전기장이 가해진 $TiO_2$의 결정이 더 잘 배열된 것을 확인하였고, 그로인해 에너지 변환 효율이 7.09%에서 8.65%로 증가한 것을 알 수 있었다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1461-1462
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• 2011

In this paper, in order to obtain the excellent transparent conducting film with low resistivity and high optical transmittance for dye sensitized solar cell, ITiO thin films were deposited on Corning glass substrate by rf magnetron sputtering method. The effects of the discharge power and gas pressure on the electrical and optical properties were investigated experimentally. Particularly in order to lower the electrical resistivity, the effect of heat treatment and bias voltage on the morphological properties of ITiO thin film were also studied and discussed. The concentration ratio (%) for In, Ti, and O was 27 : 2 : 42. The electrical resistivity of $2{\times}10^{-4}{\Omega}{\cdot}cm$ and 90% of optical transmittance were obtained under the conditions of 5mTorr of gas pressure, 300W of discharge power, $300^{\circ}C$ of substrate temperature.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1471-1472
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• 2011

최근 경재적인 한계를 드러내고 있는 실리콘 태양전지의 대안으로 주목받고 있는 염료감응형 태양전지는 식물의 광합성 원리에 기초하여 빛이 입사하면 염료 분자가 포톤을 흡수해 여기하면서 전자를 방출함으로써 기전력을 발생시키는 원리로 동작한다. 염료에서 발생된 전자는 $TiO_2$의 conduction band로 주입되어 확산을 통해 TCO 기판으로 이동한다. 이때 다공성 나노구조의 $TiO_2$ 표면과 전해질의 접촉이 발생하게 되고 이로 인해 $TiO_2$ conduction band의 전자와 전해질의 $I_3{^-}$ 간의 재결합이 발생하게 되는데 이것은 DSC의 기능을 저하시키는 요인 중의 하나이다. 이러한 문제점은 $Al_2O_3$, ZnO, MgO, $BaTiO_2$ 등의 표면처리에 의한 core-shell 나노구조를 형성함으로써 해결할 수 있다. 본 연구에서는 aluminum isopropoxidee와 magnesium chloride 혼합 용액을 사용하여 core-shell 나노구조를 형성하여 셀을 제작하고, 완성된 셀의 출력특성과 내부 임피던스의 변화를 측정, 분석함으로써 단일 용액을 사용하였을 때에 비해 효과적인 재결합 감소와 광전압의 상승효과를 확인할 수 있었다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.5
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• pp.355-358
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• 2011

As a II-IV compound semiconductor, ZnO has a wide band gap of 3.37 eV with transparent properties. Due to this transparent properties, ZnO materials can be also employed as the transparent conducting electrode materials. Recently, rapid progress has been made in the field of DSSC (dye sensitized solar cell)area. Therefore, strong demands have been required for the transparent electrodes with low temperature processing and cheap cost. In this paper, we will prepare ZnO thick films on the PET substrates for the electrode applications. We will investigate the structural and microstructure properties through the XRD, and SEM analysis, respectively. Also, we will study the electrical of specimens to apply the conducting electrode.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1258_1259
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• 2009

염료감응형 태양전지 (dye-sensitized solar cell; DSC)는 경제성 한계에 달한 Si 태양전지를 대체할 수 있는 유력한 후보로서, 지금까지 많은 연구개발로 큰 효율향상을 기록했다. 다양한 연구 분야 중에서도, 투명전도성 막과 전해질 층간의 접촉으로 발생하는 전자의 재결합을 막기 위해 삽입하는 compact layer는 ZnO dip-coating, $TiCl_4$ dip-coating, Ti sputtering 등 다양한 제조방법이 제시되었다. 본 연구에서는 $TiCl_4$ 용액을 이용해 spin-coating 방법으로 $TiO_2$ compact layer를 제조하는 시도를 했다. 기존 dip-coating 방법과의 비교를 통해서 본 연구의 spin-coating 방법에 의한 효과를 확인한 결과, standard DSC 대비 33.4%, dip-coating 방법으로 compact layer를 삽입한 DSC 대비 6%의 효율 향상을 기록했다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.317-319
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• 2007

Recently, there were many researches for efficiency improvement of DSC. Among of these works, research of surface treatment is still a prerequisite for electron diffusion, light-harvesting and surface state of $DSC^{4)}$. Using of the surface treatment, it can be raise up porosity of $TiO_{2}$ nano-crystalline structure on $photo-electrode^{5)}$. There are chemical, physical, electrical and optical methods which raise up its porosity. In this paper, we have designed and manufactured MOPA-type ultrasonic circuit (100W, frequency and duty variable). Manufactured ultrasonic circuit to use to force cavity density and power into $TiO_{2}$ paste. Then, we have optimized forcing time, frequency and duty of ultrasonic irradiation for surface treatment of photo-electrode of DSC. In I-V characteristic test of DSC, ultrasonic and thermal treated DSC shows 19% improved its efficiency against established DSC.