• 한국결정성장학회지
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• 제30권5호
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• pp.189-193
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• 2020

최근 웨어러블 센서를 구현하기 위한 유연전극을 제조하기 위한 다양한 방법들이 논의되고 있다. 현재 개발되고 있는 웨어러블 센서기기는 피부의 신축성에 따라 잘 늘어나야 하고, 신축성을 부여하기 위해, 다양한 고분자 기판이 사용되어지고 있다. 따라서, 본 논문에서는 스펀지 기반 신축성 기판에 고탄성의 은나노와이어 전극을 형성하고 신축의 정도에 따른 전기적 특성 평가를 진행하였다. 제조 방법은 습식합성법을 이용하여 은나노와이어를 성장시켰고 플라즈마 표면처리된 폴리우레탄 기반의 스펀지에 함침시킨 후 저온에서 열처리를 하였다. 특히, 스펀지의 플라즈마 표면처리는 은나노와 이어의 균일한 코팅을 가능케 하였다. 유연 스펀지 전극은 160회 이상의 반복 인장-수축 사이클에서 신뢰성있는 전기 저항변화를 보여주었다.

• 대한기계학회논문집A
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• 제38권8호
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• pp.893-898
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• 2014

펄스 레이저를 적용한 실버나노와이어의 접합 영향이 연구되었다. 조사된 레이저 펄스 에너지는 실버나노와이어 네트워크에서 실버나노와이어간에 접합을 유도하였으며 이로 인해 투명 기저위의 실버나노와이어 네트워크 박막에 전기 저항값을 조절할 수 있었다. 특히 이러한 나노네트워크에서의 접합은 개별 나노와이어의 접촉점의 형태로 발생되었고 접합의 효과는 전체 실버나노와이어 네트워크의 전기저항 변화 측정으로 평가하였다. 또한 레이저 빔 펄스폭 및 레이저 평균 출력이 나노와이어 접합 비율 평가에 적용되어 연구되었다. 실버나노와이어 네트워크의 광학 특성도 관찰되었으며 이에 레이저 공정 요소 대비 효과도 연구되었다. 최적화된 레이저빔 적용 재료처리는 특화된 국부 재료 특성 개선에 장점을 보였다. 펄스 레이저를 이용한 실버나노와이어의 재료처리의 적용과 그 효과에 대해서도 논의한다.

• Nano
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• 제13권12호
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• pp.1850146.1-1850146.9
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• 2018

The rapid development of smart textiles requires the large-scale fabrication of conductive fibers. In this study, we develop a simple, scalable and low-cost capillary-driven self-assembly method to prepare conductive fibers with uniform morphology, high conductivity and good mechanical strength. Fiber-shaped flexible and stretchable conductors are obtained by coating highly conductive and flexible silver nanowires (Ag NWs) on the surfaces of yarn and PDMS fibers through evaporation-induced flow and capillary-driven self-assembly, which is proven by the in situ optical microscopic observation. The density of Ag NWs and linear resistance of the conductive fibers could be regulated by tuning the assembly cycles. A linear resistance of $1.4{\Omega}/cm$ could be achieved for the Ag NWs-coated nylon, which increases only 8% after 200 bending cycle, demonstrating high flexibility and mechanical stability. The flexible and stretchable conductive fibers have great potential for the application in wearable devices.

• 통합자연과학논문집
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• 제6권3호
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• pp.170-175
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• 2013

Silicon nanowires were detached and obtained from silicon nanowire arrays on silicon substrate using a ultrasono-method. Silicon nanowire arrays on silicon substrate were prepared with an electroless metal assisted etching of p-type silicon. The etching solution was an aqueous HF solution containing silver nitrate. SEM observation shows that well-aligned nanowire arrays perpendicular to the surface of the silicon substrate were produced. After sonication of silicon nanowire array, an individual silicon nanowire was confirmed by FESEM. Optical characteristics of SiNWs were measured by FT-IR spectroscopy. The surface of SiNWs are terminated with hydrogen.

• 마이크로전자및패키징학회지
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• 제28권1호
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• pp.73-77
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• 2021

In this study, we report on the effects of argon plasma treatment on Ag nanowires by varying the power and duration. Sheet resistance was found to be significantly reduced to 10 ohm/sq. relative to the value of 21 ohm/sq. for the pristine sample. Such a reduction was found to be associated with welded junctions between Ag nanowires, which results in enhanced current flow. With the optimized plasma treatment conditions, the maximum and average transmittance were 76.8% and 71%, respectively. Finally, we fabricated transparent heating devices based on the methodology, which exhibited superior heating capability.

• 한국재료학회지
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• 제22권10호
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• pp.562-568
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• 2012

Metal nanowires can be coated on various substrates to create transparent conducting films that can potentially replace the dominant transparent conductor, indium tin oxide, in displays, solar cells, organic light-emitting diodes, and electrochromic windows. One issue with these metal nanowire based transparent conductive films is that the resistance between the nanowires is still high because of their low aspect ratio. Here, we demonstrate high-performance transparent conductive films with silver nanofiber networks synthesized by a low-cost and scalable electrospinning process followed by two-step sequential thermal treatments. First, the PVP/$AgNO_3$ precursor nanofibers, which have an average diameter of 208 nm and are several thousands of micrometers in length, were synthesized by the electrospinning process. The thermal behavior and the phase and morphology evolution in the thermal treatment processes were systematically investigated to determine the thermal treatment atmosphere and temperature. PVP/$AgNO_3$ nanofibers were transformed stepwise into PVP/Ag and Ag nanofibers by two-step sequential thermal treatments (i.e., $150^{\circ}C$ in $H_2$ for 0.5 h and $300^{\circ}C$ in Ar for 3 h); however, the fibrous shape was perfectly maintained. The silver nanofibers have ultrahigh aspect ratios of up to 10000 and a small average diameter of 142 nm; they also have fused crossing points with ultra-low junction resistances, which result in high transmittance at low sheet resistance.

• 한국광학회:학술대회논문집
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• 한국광학회 2006년도 하계학술발표회 논문집
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• pp.135-136
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• 2006

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.62-62
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• 2018

Pt is still considered as one of the most active electrocatalysts for ORR in alkaline fuel cells. However, the high cost and scarcity of Pt hamper the widespread commercialization of fuel cells. As a strong candidate for the replacement of Pt catalyst, silver (Ag) has been extensively studied due to its high activity, abundance, and low cost. Ag is more stable than Pt in the pH range of 8~14 as the equilibrium potential of Ag/Ag+ being ${\approx}200mV$ higher than that of Pt/PtO. However, Ag is the overall catalytic activity of Ag for oxygen reduction reaction(ORR) is still not comparable to Pt catalyst since the surface Ag atoms are approximately 10 times less active than Pt atoms. Therefore, further enhancement in the ORR activity of Ag catalysts is necessary to be competitive with current cutting-edge Pt-based catalysts. We demonstrate the architectural design of Ag catalysts, synthesized using plasma discharge in liquid phase, for enhanced ORR kinetics in alkaline media. An attractive feature of this work is that the plasma status controlled via electric-field could form the Ag nanowires or dendrites without any chemical agents. The plasma reactor was made of a Teflon vessel with an inner diameter of 80 mm and a height of 80 mm, where a pair of tungsten(W) electrodes with a diameter of 2 mm was placed horizontally. The stock solutions were made by dissolving the 5-mM AgNO3 in DI water. For the synthesis of Agnanowires, the electricfield of 3.6kVcm-1 in a 200-ml AgNO3 aqueous solution was applied across the electrodes using a bipolar pulsed power supply(Kurita, Seisakusyo Co. Ltd). The repetition rate and pulse width were fixed at 30kHz and 2.0 us, respectively. The plasma discharge was carried out for a fixed reaction time of 60 min. In case of Ag nanodendrites, the electric field of 32kVcm-1 in a 200-ml AgNO3 aqueous solution was applied and other conditions were identical to the plasma discharge in water in terms of electrode configuration, repetition rate and discharge time. Using SEM and STEM, morphology of Ag nanowires and dendrites were investigated. With 3.6 kV/cm, Ag nanowire was obtained, while Ag dendrite was constructed with 32 kV/cm. The average diameter and legth of Ag nanowireses were 50 nm and 3.5 um, and thoes values of Ag dendrites were 40 nm and 3.0 um. As a results of XPS analysis, the surface defects in the Ag nanowires facilitated O2 incorporation into the surface region via the interaction between the oxygen and the electron cloud of the adjacent Ag atoms. The catalytic activity of Ag for oxygen reduction reaction(ORR) showed that the catalytic ORR activity of Ag nanowires are much better than Ag nanodendrites, and electron transfer number of Ag nanowires is similar to that of Pt (${\approx}4$).

• 한국전기전자재료학회논문지
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• 제30권9호
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• pp.572-576
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• 2017

A hybrid transparent electrode was fabricated with graphene and silver nanowires (Ag NWs). Three different processes were used to fabricate the hybrid electrode. Measurements of the sheet resistances, transmittances, and surface roughnesses of the hybrid electrodes were used to identify the optimal fabrication process. The surface roughness of the hybrid electrodes with Ag NWs embedded in a transparent polymer matrix was significantly lower than that of the other hybrid electrodes. A hybrid electrode fabricated by transferring graphene onto Ag NWs after spin-coating the Ag NWs onto the substrate showed the lowest sheet resistance. The transmittance of the hybrid electrodes was comparable to that of Ag NW electrodes.

• 한국표면공학회지
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• 제50권6호
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• pp.486-491
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• 2017

Silver nanowire (AgNW) transparent electrode is one of next generations of flexible and transparent electrode. The electrode shows high conductivity and high transparency comparable to ITO. However, the electrode is weak against heat. The wires are separated into nanodots at temperature above $200^{\circ}C$. It causes the electrical resistance increase. Moreover, it is vulnerable to oxygen and moisture in the atmosphere. The improvement of thermal and moisture resistance of silver nanowire transparent electrode is the most important for commercializing. We proposed silver nanowires transparent electrode which is capped with very thin nickel oxide layer. The nickel oxide layer is five nanometers of thickness, but the heat and moisture resistance of the transparent electrode is effectively improved. The AgNW/NiO electrode can endure at $300^{\circ}C$ of temperature for 30 minutes, and resistance is not increased for 180 hours at $85^{\circ}C$ of temperature and 85% of relative humidity. We showed an applications of transparent and flexible heater using the electrode, the heater is operated more than $180^{\circ}C$ of temperature.