• 센서학회지
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• 제17권6호
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• pp.418-424
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• 2008

The PZT based piezoelectric thick films prepared by screen printing method have been mainly used as a functional material for MEMS applications due to their compatibility of MEMS process. However the screen printed thick films generally reveal poor electrical and mechanical properties because of their porous microstructure. To improve microstructure we mixed attrition milled powder with ball milled powder of 0.01Pb$(Mg_{1/2}W_{1/2})O_3$-0.41Pb$(Ni_{1/3}Nb_{2/3})O_3$-$0.35PbTiO_3$-$0.23PbZrO_3$+0.1 wt% ${Y_2}{O_3}$+1.5 wt% ZnO composition. By mixing 25 % of attrition milled powder and 75 % of ball milled powder, the broadest particle size distribution was obtained, leading to a dense thick film with crack-free microstructure and improved dielectric properties. The X-ray diffraction analysis revealed that the film was in wellcrystallized perovskite phase. The remanent polarization was increased from $13.7{\mu}C/cm^2$ to $23.3{\mu}C/cm^2$ at the addition of 25 % attrition milled powder.

• 공업화학
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• 제32권4호
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• pp.456-460
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• 2021

본 연구에서는 탄소 및 은 잉크를 사용하여 스크린 인쇄 공정을 통한 전위차 나트륨 이온(Na⁺) 센서를 제작하였다. 센서의 두 전극 구성은 Na⁺ 용액에서 네른스트 거동에 따라 전극의 전위차를 발생하였다. 제조된 Na⁺ 센서는 이상적인 네른스트 민감도, 빠른 응답 시간 및 낮은 검출 한계를 보여주었다. 네른스트 반응은 센서의 반복성 및 장기 내구성 테스트 시 안정적이었다. 탄소 전극에 코팅된 Na⁺ 선택막은 간섭 이온에 대해 나트륨 이온을 선택적으로 통과시켜 우수한 선택성을 증명하였다. 휴대용 Na⁺ 센서는 인쇄 회로 시스템을 사용하여 제작되었으며 다양한 실제 샘플에서 Na⁺ 농도를 성공적으로 측정하는 것을 증명하였다.

• Current Photovoltaic Research
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• 제9권4호
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• pp.128-132
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• 2021

Advances in screen printing technology have been led to development of high efficiency silicon solar cells. As a post PERx structure, an n-type wafer-based rear side TOPCon structure has been actively researched for further open-circuit voltage (Voc) improvement. In the case of the metal contact of the TOPCon structure, the poly-Si thickness is very important because the passivation of the substrate will be degraded when the metal paste penetrates until substrate. However, the thin poly-Si layer has advantages in terms of current density due to reduction of parasitic absorption. Therefore, poly-Si thickness and firing temperature must be considered to optimize the metal contact of the TOPCon structure. In this paper, we varied poly-Si thickness and firing peak temperature to evaluate metal induced recombination (Jom) and contact resistivity. Jom was evaluated by using PL imaging technique which does not require both side metal contact. As a results, we realized that the SiN_x deposition conditions can affect the metal contact of the TOPCon structure.

• Current Photovoltaic Research
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• 제11권2호
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• pp.44-48
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• 2023

In heterojunction technology (HJT) solar cells, low-temperature curing paste is used because the passivation layer deteriorates at high temperatures of 200℃ or higher. However, manufacturing HJT photovoltaic (PV) modules is challenging due to the weak peel strength between busbar electrodes and cells after soldering process. For this issue, the electrode thicknesses of the busbars of the HJT solar cell were analyzed, and the peel strengths between electrodes and wires were measured after soldering using an infrared (IR) lamp. As a result, the electrodes printed by the screen printing method had a difference in thickness due to screen mask. Also, as the thickness of the electrode increased, the peel strength of the wire increased.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.61.2-61.2
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• 2010

Ag thick-film has usually been used for the front electrode of Si solar cells with the outstanding electrical properties. Ag paste consists of Ag powers, vehicles, frits and additives. Ag paste has broadly been screen-printed on the front side of Si wafer with the merits of low cost and simplicity. The optimal contact formation between Ag electrodes and Si wafer in the front electrode during a fast firing has been considered as the key factor for high efficiency. Although the content of frit in Ag pastes is less than 5wt%, it can profoundly influence the contact formation between Ag and Si under the fast firing. In this study, the effects of lead-free frits on the contacts between Ag and Si were studied with the thermal properties and compositions of various frits. Our experimental results showed that the electrical properties of cells were related to the interface structures between Ag and Si. It was found that current path of electrons from Si to Ag would be possible through the tunneling mechanism assisted by tens of nano-Ag recrystals on $n^+$ emitter as well as Ag recrystals penetrated into $n^+$ emitter layers. These preliminary studies will be helpful for designing the proper frits for the Ag pastes with considering the properties of various Si wafers.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.91.2-91.2
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• 2010

The use of plated front contact for metallization of silicon solar cell may alternative technologies as a screen printed and silver paste contact. This technologies should allow the formation of contact with low contact resistivity a high line conductivity and also reduction of shading losses. The better performance of Ni/Cu contacts is attributed to the reduced series resistance due to better contact conductivity of Ni with Si and subsequent electroplating of Cu on Ni. The ability to pattern narrower grid lines for reduced light shading combined with the lower resistance of a metal silicide contact and improved conductivity of plated deposit. This improves the FF as the series resistance is deduced. This is very much required in the case of low concentrator solar cells in which the series resistance is one of the important and dominant parameter that affect the cell performance. A selective emitter structure with highly dopes regions underneath the metal contacts, is widely known to be one of the most promising high-efficiency solution in solar cell processing. This paper using selective emitter structure technique, fabricated Ni/Cu plating metallization cell with a cell efficiency of 17.19%.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.42.1-42.1
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• 2010

결정질 실리콘 태양전지의 전면 전극은 전극 면적으로 인한 손실(shading loss)를 줄이고 단락전류밀도(Jsc)를 높이기 위해 전극 너비를 줄이는 노력을 하고 있다. 하지만 전극 소성(firing) 시 전면 전극의 핑거(finger)와 버스바(busbar)의 너비 차이로 인해 전극 침투(fire-through) 정도가 달라질 수 있다. 본 연구에서는 전극 소성 공정 시 전면 전극의 너비에 따른 전극 침투 정도를 조사하기 위해 접촉 저항(specific contact resistance)과 재결정화(Ag recrystallite) 된 전면전극의 분포에 대해 비교하였다. 접촉 저항을 측정하기 위하여 transfer length method(TLM)를 이용하였다. 또한 전면 전극층을 제거한 후 실리콘 기판의 재결정 분포를 주사전자현미경(Scanning electron microscope : SEM)을 이용하여 관찰하였다.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2803-2808
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• 2014

High potential and fast electron transfer of a cathode mediator are significant factors for improving the performance of biofuel cells. This paper reports the first synthesis of a cathode redox polymer that is a coordination complex of poly (acrylic acid-vinylpyridine-acryl amide) (PAA-PVP-PAA) and [Os(4,4'-dicarboxylic acid-2,2'-bipyridine)$_2Cl_2]^{/+}$ ($E^{\circ}=0.48V$ versus Ag/AgCl). Bilirubin oxidase can be easily incorporated into this polymer matrix, which carried out the four-electron oxygen under typical physiological conditions (pH 7.2, 0.14 M NaCl, and $37^{\circ}C$). This new polymer showed an approximately 0.1 V higher redox potential than existing cathode mediators such as PAA-PVI-$[Os(dCl-bpy)_2Cl]^{+/2+}$. In addition, we suggest increasing the polymer solubility with two hydrophilic groups present in the polymer skeleton to further improve fast electron transfer within the active sites of the enzyme. The maximum power density achieved was 60% higher than that of PAA-PVI-$[Os(dCl-bpy)_2Cl]^{+/2+}$. Furthermore, high current density and electrode stability were confirmed for this osmium polymer, which makes it a promising candidate for high-efficiency biofuel cells.

• Current Photovoltaic Research
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• 제4권1호
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• pp.12-15
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• 2016

Screen printing technique followed by firing has commonly been used as metallization for both laboratory and industrial based solar cells. In the solar cell industry, the firing process is usually conducted in a belt furnace and needs to be optimized for fabricating high efficiency solar cells. The printed-Al layer on the silicon is rapidly heated at over $800^{\circ}C$ which forms a layer of back surface field (BSF) between Si-Al interfaces. The BSF layer forms $p-p^+$ structure on the rear side of cells and lower rear surface recombination velocity (SRV). To have low SRV, deep $p^+$ layer and uniform junction formation are required. In this experiment, firing process was carried out by using conventional tube furnace with $N_2$ gas atmosphere to optimize $V_{oc}$ of laboratory cells. To measure the thickness of BSF layer, selective etching was conducted by using a solution composed of hydrogen fluoride, nitric acid and acetic acid. The $V_{oc}$ and pseudo efficiency were measured by Suns-$V_{oc}$ to compare cell properties with varied firing condition.

• 한국세라믹학회지
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• 제52권4호
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• pp.264-268
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• 2015

Cu films were plated in an eco-friendly electroless bath (No-Formaldehyde) on Ni/screen printed Ag pattern/PET substrate. For electroless Cu plating, we used sodium-phosphinate ($NaH_2PO_2{\cdot}H_2O$) as reducing agent instead of Formaldehyde. All processes were carried out in electroless solution of pH 7 to minimize damage to the PET substrate. According to the increase of sodium-phosphinate, the deposition rate, the granule size, and rms roughness of the electroless Cu film increased and the Ni content also increased. The electroless Cu films plated using 0.280 M and 0.575 M solutions of sodium-phosphinate were made with Cu of 94 at.% and 82 at.%, respectively, with Ni and a small amount P. All electroless Cu plated films had typical FCC crystal structures, although the amount of co-deposited Ni changed according to the variation of the sodium-phosphinate contents. From these results, we concluded that a formation of higher purity Cu film without surface damage to the PET is possible by use of sodium-phosphinate at pH 7.