• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.321-321
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• 2010

일반적으로 결정질 silicon solar cell의 에미터 층의 면저항이 높아짐에 따라 표면에서의 재결합이 줄어들고, Voc가 상승한다. 그러나 에미터 층의 면저항이 높을 경우 전면에서의 전극 저항과 에미터에 흐르는 캐리어에 의한 저항 손실이 커져 태양전지의 효율을 저하시키는데, 이를 해결하기 위한 방법으로 selective emitter에 대한 연구가 진행되고 있지만 이는 공정 과정이 다소 복잡하다는 단점이 있다. 본 연구에서는 투명 전도막 재료 중의 하나인 ITO를 결정질 실리콘 태양전지에 적용하여 위의 문제점을 해결하였다. 낮은 농도로 도핑한 에미터 층 위에 ITO를 증착시켜 cell을 제작하였으며, 완성된 high Rs cell의 결과를 기존의 low Rs cell의 특성과 비교, 분석하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.10
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• pp.902-907
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• 2003

In this paper, the ITO thin film, which is considered as one of the most currently used material for the high performance transparent conducting films for the PDP cell, was made in a parallel-plate, capacitively coupled DC magnetron sputtering system. Some electrical and optical properties of ITO films were investigated and discussed on the basis of glow discharge characteristics. The optimized thin film fabricating conditions of Ar gas pressure and substrate temperature were derived from the Paschen curve and glow discharge characteristics. The maximum transmittance of 89.61 % in the visible region and optical band gap of 3.89 eV and resistivity of 1.67${\times}$10$\^$-3/ $\Omega$-cm were obtained under the conditions of 300 C of substrate temperature and 10∼15 mtorr of pressure, which corresponds nearly to that of Paschen minimum.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1411-1413
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• 1997

The thin film that is electrically conductive and optically transparent is called conductive transparent thin film. ITO(Indium-Tin Oxide) which is a kind of conductive transparent thin film has been widely used in solar cell, transparent electrical heater, selective optical filter, FDP(Flat Display Panel) such as LCD (Liquid Crystal Display), PDP(Plasma Display Panel) and so on. Especially in PDP, ITO films is used as a transparent electrode in order to maintain discharge and decrease consumption power through the improvement of cell structure. In this study, we prepared ITO by reactive r.f. sputtering with indium-tin(Sn wt 10%) alloy target instead of indium-tin oxide target. The ITO films deposited at low temperature $150^{\circ}C$ and 8% $O_2$ partial pressure showed about $3.6{\Omega}/{\square}$. At the end of firing, the resistance of ITO was decreased, the optical transparence was improved above 90%.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2689-2693
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• 2012

Single-walled carbon nanotubes (SWNTs) and $C_{60}$-encapsulated SWNTs ($C_{60}@SWNTs$) are introduced to Ru-sensitized photoelectrochemical cells (PECs), and photocurrents are compared between two cells, i.e., an $RuL_2(NCS)_2$/DAPV/SWNTs/ITO cell and an $RuL_2(NCS)_2$/DAPV/$C_{60}@SWNTs$/ITO cell. [L = 2,2'-bipyridine-4,4'-dicarboxylic acid, DAPV = di-(3-aminopropyl)-viologen, and ITO = indium-tin oxide] The photocurrents are increased by 70.6% in the presence of $C_{60}@SWNTs$. To explain the photocurrent increase, the reverse-field emission method is used, i.e., $RuL_2(NCS)_2$/DAPV/SWNTs/ITO cell (or $RuL_2(NCS)_2$/DAPV/$C_{60}@SWNTs$/ITO cell) as an anode and a counter electrode Pt as a cathode in the external electric field. The improved field emission properties, i.e., ${\beta}$ (field enhancement factor) and emission currents in the reverse-field emission with $C_{60}@SWNTs$ indicate the enhancement of the PEC electric field, which implies the improvement of the electron transfer rate along with the reduced charge recombination in the cell.

• Solar Energy
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• v.19 no.3
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• pp.125-131
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• 1999

This paper deals with a novel structure of poly-Si solar cell. A grain boundary(GB) of poly-Si acts as potential barrier and recombination center for photo-generated carriers. To reduce unwanted side effects at the GB of poly-Si, we employed physical GB removal of poly-Si using chemical solutions. Various chemical etchants such as Sirtl, Yang, Secco, and Schimmel were investigated for the preferential GB etching. Etch depth about 10 ${\mu}m$ was achieved by a Schimmel etchant. After a chemical etching of poly-Si, we used $POCl_3$ for emitter junction formation. This paper used an easy method of top electrode formation using a RF sputter grown ITO film. ITO films with thickness of 300 nm showed resistivity of $1.26{\times}10^{-4}{\Omega}-cm$ and overall transmittance above 80%. Using a preferential GB etching and ITO top electrode, we developed a new fabrication procedure of poly-Si solar cells. Employing optimized process conditions, we were able to achieve conversion efficiency as high as 16.6% at an input power of 20 $mW/cm^2$. This paper investigates the effects of process parameters: etching conditions, ITO deposition factors, and emitter doping densities in a poly-Si cell fabrication procedure.

• Textile Coloration and Finishing
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• v.20 no.1
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• pp.44-47
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• 2008

Organic semi-conductive materials have characteristics such as the advantages of easy formability, low-cost and diversity along with moderate semi-conductive properties. In this paper, we developed a flexible organic-inorganic hybrid solar cell fiber. First, we made a solar cell on the glass and attached the solar cell on the glass fiber similarly. In the latter case, thermal deposition method was employed in order to effectively apply ITO onto fiber surface. The amount of ITO was controlled by varying the temperature from 25, 150 to $300^{\circ}C$. Optimum result was obtained at $150^{\circ}C$ where maximize the deposition amount without significant decomposition of ITO. Despite of maximum open circuit voltage of 0.39V, the resulting current was quite unstable and weak, limiting realistic applications. It was, however, concluded that the flexible solar cell fiber developed showed a possibility of low-weight application from functional clothing for military to space suit mainly due to flexibility and thus wear ability.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1144-1148
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• 2006

We have investigated liquid crystal (LC) aligning capabilities and electro-optical (EO) characteristics of transparent electrodes as Al-doped ZnO (AZO) substituting indium tin oxide (ITO). The experiment results show that a uniform vertical LC alignment on AZO electrodes based on a rubbed polyimide (PI) surface were achieved. A high pretilt angle of about $88^{\circ}$ was obtained. EO performances of the VA cell on rubbed PI surfaces with AZO electrodes are almost the same as that of the VA cell with ITO electrodes. These results appeared that AZO electrodes as transparent electrodes of LCDs could substitute ITO electrodes.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.6-6
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• 2010

Indium Tin Oxide (ITO)를 포함한 Transparent Conduction Oxide (TCO)는 LCD, OLED와 같은 Display, 그리고 Solar Cell 등 광신호와 전기신호간 변환이 필요한 모든 Device에 반드시 필요한 핵심 물질로, 특히 고특성 Display의 투명전극에서 요청되는 95% 이상의 투과도와 $15\;{\Omega}/{\square}$ 이하의 면저항 특성을 동시에 만족할 수 있는 기술은 현재까지 Plasma Sputtering 공정으로 $160^{\circ}C$ 이상에서 증착된 ITO 박막이 유일하다. 그러나, 최근 차세대 기술로서 Plastic Film을 기반으로 하는 Flexible Display 및 Flexible Solar Cell 구현에 대한 요구가 급증하면서, Plastic Film 기판위에 Plasma Damage이 없이 상온에 가까운 저온 ($100^{\circ}C$ 이하)에서 특성이 우수한 ITO 투명전극을 형성 할 수 있는 기술의 확보가 중요한 현안이 되고 있다. 지난 10년 동안 $100^{\circ}C$이하 저온에서 고특성의 ITO 또는 TCO 박막을 얻기위한 다양한 연구와 구체적인 공정이 활발히 연구되어 왔으나, ITO의 결정화 온도 (통상 $150{\sim}180^{\circ}C$)이하에서 증착된 ITO박막은 비정질 상태의 물성적 특성을 보여 원하는 전기적, 광학적 특성확보가 어려웠다. 본 논문에선 기본적으로 절연체 특성을 가져야 하는 산화물인 TCO가 반도체 또는 도체의 물리적 특성을 보여주는 기본원리의 고찰을 토대로, 재료학적 특성상 Crystalline 구조를 보여야 하는 ITO (Complex Cubic Bixbyte Structure)가 Plasma Sputtering 공정으로 저온에서 증착될 때 비정질 구조를 갖게 되는 원인을 규명하고, 이를 바탕으로 저온에서 증착된 ITO가 Crystalline 구조를 유지 할 수 있게 하고, Stress Control에 유리한 Nano-Crystalline 박막을 형성하면서 Crystallinity를 임의로 조절 할 수 있는 새로운 기술인 Magnetic Field Shielding Sputtering (MFSS) 공정과 최근 성과를 소개한다. 한편, 또 다른 새로운 저온 TCO 박막형성 기술로서, 유기반도체와 같은 Process Damage에 매우 취약한 유기물 위에 Plasma Damage 없이 TCO 박막을 직접 형성할 수 있는 Neutral Beam Assisted Sputtering (NBAS) 기술의 원리를 설명하고, 본 공정을 적용한 Top Emission OLED 소자의 결과를 소개한다. 또한, 고온공정이 수반되는 Solar Cell용 투명전극의 경우, 통상의 TCO박막이 고온공정을 거치면서 전기적 특성이 열화되는 원인을 규명하고, 이에 대한 근본적 해결 방법으로 ITO 박막의 Dopant인 Tin (Sn) 원자의 활성화를 증가시킨 Inductively Coupled Plasma Assisted DC Magnetron Sputtering (ICPDMS)의 원리와 박막의 물성적 특성과 내열 특성을 소개한다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.257.1-257.1
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• 2014

We investigated characteristics of ITO/Ag-Pd-Cu (APC)/ITO multilayer electrodes prepared by direct current magnetron sputtering for use as an anode in organic solar cells (OSCs). To optimize electrical properties of ITO/APC/ITO multilayer, we fabricated the ITO/APC/ITO multilayer at a fixed ITO thickness of 30 nm as a function of APC thickness. Compare to the surface of Ag layer on ITO, the APC had a smooth surface morphology. At optimized APC thickness of 12 nm, the ITO/APC/ITO multilayer exhibited a sheet resistance of $6{\Omega}/square$ and optical transmittance of 84.15% at a wavelength of 550 nm which is comparable to conventional ITO/Ag/ITO multilayer. However, the APC-based ITO multilayer showed a higher average transmittance in a visible region than the Ag-based ITO multilayer. The higher average transmittance of ITO/APC/ITO multilayer indicated the multilayer is suitable anode for organic solar cells with P3HT:PCBM active layer. OSCs fabricated on the optimized ITO/ACP/ITO multilayer exhibited a better performance with a fill factor of 64.815%, a short circuit current of $8.107mA/cm^2$, an open circuit voltage of 0.59 V, and power conversion efficiency (3.101%) than OSC with ITO/Ag/ITO multilayer (2.8%).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.597-600
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• 1999

A solar cell conversion efficiency was degraded by grain boundary effect in polycrystalline silicon To reduce grain boundary effect, we performed a preferential grain boundary etching, POC$_3$ n-type emitter doping, and then ITO film growth on poly- Si. Among the various preferential etchants, Schimmel etch solution exhibited the best result having grain boundary etch depth higher than 10 ${\mu}{\textrm}{m}$. RF magnetron sputter grown ITO films showed a low resistivity of 10$^{-4}$ $\Omega$ -cm and high transmittance of 85 %. With well fabricated poly-Si solar cells, we were able to achieve as high as 15 % conversion efficiency at the input power of 20 mW/$\textrm{cm}^2$.