• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.27.2-27.2
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• 2011

Polymer electronics is the one of the most promising way to realize the flexible electronics and many studies made remarkable progress to achieve the improvement in performance of polymer electronics comparable to current silicon-based technology. PBTTT is conjugated semiconducting polymer with highly ordered, chain-extended crystalline microstructures and shows high field effect mobilities above 0.1 $cm^2/Vs$. We studied PBTTTs FETs phase and explored methods to control channel interface in various device structures. Especially, in PBTTTs' unique nano-ribbon phase, we could obtain high mobilities of up to 0.4 $cm^2/Vs$, which was not reached before. Alignment of PBTTTs film was carried out using zone casting and anisotropy of mobilities in parallel and perpendicular to the polymer chain direction was investigated. Optical anisotropy in aligned nano-ribbon PBTTT FETs was also studied using a polarized optical absorption.

• Current Photovoltaic Research
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• 제4권2호
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• pp.59-63
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• 2016

A key point of a soldering process for photovoltaic (PV) modules is to increase an adhesive strength leading a low resistivity between ribbon and cell. In this study, we intended to optimize a heating condition for the soldering process and characterize the soldered joint via physical and chemical analysis methods. For the purpose, the heating conditions were adjusted by IR lamp power, heating time and hot plate temperature for preheating a cell. Since then the peel test for the ribbon and cell was conducted, consequently the peel strength data shows that there is some optimum soldering condition. In here, we observed that the peel strength was modified by increasing the heating condition. Such a soldering property is affected by a various factors of which the soldered joint, flux and bus bar of the cell are changed on the heating condition. Therefore, we tried to reveal causes determining the soldering property through analyzing the soldered interface.

• 한국전기전자재료학회논문지
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• 제36권2호
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• pp.186-190
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• 2023

We studied the various characteristics of Sn-In (wt%) Pb-free solders for photovoltaic ribbon application. The solders near the eutectic composition of Sn₄₈In₅₂ (wt%) existed in InSn₄ and In₃Sn alloy phases, and in In crystal phase, but not in Sn crystal phase. In addition, the InSn₄ phase (γ-alloy) existed separately from the In₃Sn (β-alloy) and the In phase confirmed by an SEM-EDS-mapping. The melting temperature of the eutectic solder of Sn₄₈In₅₂ (wt%) was 119.2℃, and when the Sn content decreased in reference to the eutectic composition, it slightly increased to 121.4℃, but when the Sn content increased, it remained almost constant at 119.1℃. The peel strength of the ribbon plated with the Sn₄₂In₅₈ (wt%) solder was 38.7 N/mm², and it tended to increase when the Sn content increased. The peel strength of the eutectic Sn₄₈In₅₂ (wt%) solder was 53.6 N/mm², and that of the Sn₅₁In₄₉ (wt%) solder was 61.6 N/mm² that was the highest.

• Current Photovoltaic Research
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• 제11권4호
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• pp.114-117
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• 2023

Transparent Photovoltaic (PV) modules have recently been in the spotlight because they can be applied to buildings and vehicles. However, crystalline silicon (c-Si) solar modules, which account for about 90% of the PV module market, have the disadvantage of applying transparent PV modules due to their unique opacity. Recently, a see-through type PV module using a crystalline silicon solar strap has been developed. However, there is a problem due to a decrease in aesthetics due to the metal ribbon in the center of the see-through type PV module and difficulty bonding the metal ribbon due to the low voltage output of the strap. In this study, to solve this problem, we developed a fabrication process of series connected c-Si solar strap cells using the c-Si solar cells. We succeeded in fabricating a series connected strap with a width of 2-10 mm, and we plan to manufacture an aesthetic see-through type c-Si PV module.

• 한국재료학회지
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• 제23권3호
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• pp.190-193
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• 2013

Spatial distributions of alloying elements of an Fe-based amorphous ribbon with a nominal composition of $Fe_{75}C_{11}Si_2B_8Cr_4$ were analyzed through the atom probe tomography method. The amorphous ribbon was prepared through the melt spinning method. The macroscopic amorphous natures were confirmed using an X-ray diffractometer (XRD) and a differential scanning calorimeter (DSC). Atom Probe (Cameca LEAP 3000X HR) analyses were carried out in pulsed voltage mode at a specimen base temperature of about 60 K, a pulse to base voltage ratio of 15 %, and a pulse frequency of 200 kHz. The target detection rate was set to 5 ions per 1000 pulses. Based on a statistical analyses of the data obtained from the volume of $59{\times}59{\times}33nm^3$, homogeneous distributions of alloying elements in nano-scales were concluded. Even with high carbon and strong carbide forming element contents, nano-scale segregation zones of alloying elements were not detected within the Fe-based amorphous ribbon. However, the existence of small sub-nanometer scale clusters due to short range ordering cannot be completely excluded.

• Transactions on Electrical and Electronic Materials
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• 제15권3호
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• pp.155-158
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• 2014

The phase transformation of Sn-Pb-Bi solder for photovoltaic ribbon during soldering was studied using real-time synchrotron x-ray scattering. At room temperature, Sn and Pb crystal phases in the solder existed separately. By heating to $92^{\circ}C$, a new PbBi alloy crystal phase was formed, which grew further up to $160^{\circ}C$. The Sn crystal phase first started to melt at $160^{\circ}C$, and was mostly melted at $165^{\circ}C$. In contrast, the Pb and PbBi crystal phases started to melt at $165^{\circ}C$, and were mostly melted at $170^{\circ}C$. The useful result was obtained, that the solder's melting temperature decreased from $183^{\circ}C$ to $170^{\circ}C$ by addition of a small amount of Bi atoms to the eutectic Sn62-Pb38 (wt%) solder. Our study first revealed the detailed in-situ phase transformation of Sn-Pb-Bi solder during heating to the eutectic temperature. Considering the results of peel strength and hardness, adding 1 wt% of Bi atoms to the Sn62-Pb38 (wt%) solder produced an appropriate composition.

• Journal of Electrochemical Science and Technology
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• 제3권4호
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• pp.178-184
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• 2012

A porous nickel (P-Ni) substrate was prepared by selective leaching of zinc from pressed pellets containing powders of Ni & Zn in 4 M NaOH solution. Anodic deposition of manganese oxide onto the porous Ni substrate ($MnO_x$/P-Ni) formed nano-flakes of manganese oxide layers as revealed in SEM studies. Pseudocapacitance of this oxide electrode was evaluated by cyclic voltammetry (CV) and chronopotentiometry (CHP) in 2 M NaOH solution. The specific capacitance of the Mn oxide electrode was as high as 1515 F $g^{-1}$, which was ten times higher than Mn oxide deposited on a flat Ni-ribbon. 80% of capacity was retained after 200 charge/discharge cycles. The system showed no loss of activity in dry form over period of days. The impedance studies indicated highly conducting $MnO_x$/P-Ni substance and the obtained specific capacitance from impedance data showed good agreement with the charge/discharge measurements.

• 전기전자학회논문지
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• 제23권2호
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• pp.599-605
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• 2019

페라이트 코어는 연자성 재료로서 유도형 전력선 통신을 위한 결합기 제작에 사용되고 있다. 그러나 전력선 통신환경에 따라 크기를 자유롭게 조절하기 어려운 재료이다. 본 논문에서는 페라이트 보다 투자율이 높은 나노 결정립합금을 이용하여 광대역 전력선 통신용 유도형 결합기 재료로 적용할 수 있음을 보고한다. 나노결정립은 얇은 리본 형태로 제조되므로 토로이달 코어에 감긴 리본의 횟수로 결합기의 크기를 자유롭게 조절할 수 있다. 함침법으로 만든 코어를 이용하여 유도형 결합기를 제작하였고, 이를 비접촉식 전력선 통신용에 적용할 수 있음을 보여주었다. 실험결과 100 A 이하의 선로 전류변동 조건에서 통신거리 100 m 까지는 45 Mbps, 200 m 까지는 8 Mbps의 대역폭을 보였으며 수신율은 100 %이였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1190-1190
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• 2006

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.29-29
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• 2010

기존의 반도체 공정을 기반으로 하는 소자구조는 주로 평면의 웨이퍼상에 만들어져왔다. 그러나, 제작된 소자 어레이를 늘림이 가능한 (stretchable) 폴리머 기판에 프린팅 전이하는 방식을 이용하면 어떤 형태의 곡면에도 소자 제작이 가능해진다. 이러한 프린팅 방식으로, 다양한 곡면에 실리콘 소자 어레이를 제작한 연구결과를 발표하고자 한다. 한 응용 예로 사람의 눈과 같은 반구형 표면에 실리콘 나노 리본으로 만든 광다이오드 어레이를 배열하여 전자 눈 카메라를 제작하여 성능을 확인하였다. 또한 수차를 최소화할 수 있는 포물면에 전자눈 카메라를 제작하여 평면카메라에 비해 이미지의 균일성이 우수함을 보여주고자 한다.