• 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.

• 한국재료학회지
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• 제29권2호
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• pp.87-91
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• 2019

We report on stretchable electrochromic films of poly(3-hexylthiophene) (P3HT) fabricated on silver nanowire (AgNW) electrodes. AgNWs electrodes are prepared on polydimethylsiloxane (PDMS) substrates using a spray coater for stretchable electrochromic applications. On top of the AgNW electrode, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is introduced to ensure a stable resistance over the electrode under broad strain range by effectively suppressing the protrusion of AgNWs from PDMS. This bilayer electrode exhibits a high performance as a stretchable substrate in terms of sheet resistance increment by a factor of 1.6, tensile strain change to 40 %, and stretching cycles to 100 cycles. Furthermore, P3HT film spin-coated on the bilayer electrode shows a stable electrochromic coloration within an applied voltage, with a color contrast of 28.6 %, response time of 4-5 sec, and a coloration efficiency of $91.0cm^2/C$. These findings indicate that AgNWs/PEDOT:PSS bilayer on PDMS substrate electrode is highly suitable for transparent and stretchable electrochromic devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.467.2-467.2
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• 2014

유기태양전지는 친환경 에너지 소스로써 저가 대량 생산이 가능하고 특히 유연한 기판에 적용이 가능하여 많은 관심을 받고 있다. 그럼에도 불구하고 기존에 사용되는 indium tin oxide (ITO)의 사용으로 인한 유연성 부족으로 대체되는 투명전극의 개발이 요구되어지고 있다. 이로 인해 carbon nanotubes, graphene, thin metals, metal grids, and conducting polymers 등이 연구되고 있으며, 이중 Silver nanowires (Ag NWs)를 이용한 방식도 많은 관심과 함께 전기광학적 특성에 대한 연구가 진행되고 있다. 하지만 유기전자소자에 사용되기에는 몇 가지 문제점이 발생하는데 이를 해결하기 위한 노력이 다양하게 이루어지고 있다. 특히 다양한 물질의 혼합을 통해 개선하고자 하는 노력이 증가하고 있는데 적층구조의 전도성필름 형성을 통해 ITO-free OPVs에서 Ag nanowire를 transparent conductive electrodes로 활용하였다. Ag NWs층과 PEDOT:PSS layer의 복합화를 통해 저가의 ITO-free OPVs용 transparent anodes가 가능해졌다.

• 반도체디스플레이기술학회지
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• 제17권2호
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• pp.1-5
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• 2018

Elastic resistive pressure sensor is fabricated by a direct spray coating of silver nanowires (AgNWs) on uncured polydimethylsiloxane (PDMS) and an additional coating of a conductive polymer, poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS). To improve the sensitive and stability, we have fabricated sandwich-structured AgNW/polymer sensor where two AgNW/polymer-coated PDMS films are laminated with the conducting surfaces contacted by pressure lamination. It shows a resistance decrease upon loading due to the formation of dense network of AgNWs. It is demonstrated that the sandwich-structured AgNW/polymer sensor exhibits very high sensitivity ($2.59kPa^{-1}$) and gauge factor (37.8) in the low pressure regime. It can also detect a subtle placement and removal of a weight as low as 3.4 mg, the corresponding pressure of which is about 5.4 Pa. It is shown that the protrusion of AgNWs from PDMS is suppressed substantially by the over-coated PEDOT:PSS layer, thereby reducing hysteresis and rendering the sensor more stable.

• 한국전기전자재료학회논문지
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• 제30권10호
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• pp.609-614
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• 2017

The proposed stretchable transparent electrodes based on silver nanowires (AgNWs) were prepared on a polyurethane (PU) substrate. In order toavoid the surface roughness caused by the silver nanowires, a titanium oxide ($TiO_2$) buffer layer was addedby coating and heating the organometallic sol-gel solution. The fabricated stretchable electrodes showedan electrical sheet resistance of $24{\Omega}sq^{-1}$, 78% transmittance at 550 nm, and an average surface roughness below 5 nm. Furthermore, the AgNW-based electrode maintained its initial electrical resistance under 130% strain testing conditions, without the assistance of additional conductive polymer layers. In this paper, the critical role of the $TiO_2$ buffer layer between the AgNW network and the PU substrate has been discussed.

• 한국정밀공학회지
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• 제32권10호
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• pp.903-909
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• 2015

In this study, we used GO (graphene oxide) in order to enhance the adhesion between Ag NWs (nanowires) and substrates. By using a mixture solution of GO and Ag NW, a vacuum filtration process was used to fabricate a 50nm diameter thin film. Next, by using a light annealing process, the mechanical and electrical stability of Ag NW network was improved without any other treatment. The physical properties of the Ag NW - GO hybrid transparent conductive thin film was characterized in terms of a bending test, resistance and transmittance test, and nanoscale imaging using field-emission scanning electron microscopy.

• Current Photovoltaic Research
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• 제3권4호
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• pp.116-120
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• 2015

A hybrid transparent conducting layer was applied for Si photodetector. To realize the hybrid transparent conducting layer, a 200 nm-thick ITO layer was deposited onto a Si substrate, following by a solution-processed AgNWs-coating on the ITO. The hybrid transparent conducting layer showed an excellent low electric resistance of $15.9{\Box}/{\Omega}$ with a high optical transparency of 86.89%. Due to these optical and electrical benefits, the hybrid transparent conductor-embedding Si diode provides an extremely high rectifying ratio of 3386. Under light-illumination, the hybrid transparent conductor device provides extremely high photoresponses for broad wavelengths. This implies that a functional design for hybrid transparent conductor is crucial for photoelectric devices and applications.

• 마이크로전자및패키징학회지
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• 제21권2호
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• pp.1-11
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• 2014

Flexible transparent conductive electrodes (TCEs) have recently attracted a great deal of attention owing to rapid advances in flexible electronic devices, such as flexible displays, flexible photovoltanics, and e-papers. As the performance and reliability of flexible electronics are critically affected by the quality of TCE films, it is imperative to develop TCE films with low resistivity and high transparency as well as high flexibility. Indium tin oxide (ITO) has been the most dominant transparent conducting material due to its high optical transparency and electrical conductivity. However, ITO is susceptible to cracking and delamination when it is bent or deformed. Therefore, various types of flexible TCEs, such as carbon nanotube, conducting polymers, graphene, metal mesh, Ag nanowires (NWs), and metal mesh have been extensively investigated. Among several options to replace ITO film, Ag NWs and metal mesh have been suggested as the promising candidate for flexible TCEs. In this paper, we focused on Ag NWs and metal mesh, and summarized the current development status of Ag NWs and metal mesh. The several critical issues such as high contact resistance and haze are discussed, and newly developed technologies to resolve these issues are also presented. In particular, the flexibility and durability of Ag NWs and metal mesh was compared with ITO electrode.

• 마이크로전자및패키징학회지
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• 제26권3호
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• pp.37-41
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• 2019

Ag나노와이어 도전성 잉크를 플렉서블한 투명 기판 위에 코팅 후 이러한 여분의 유기물을 $O_2$ 플라즈마를 이용하여 제거함으로써 Ag 나노와이어를 이용한 투명전극의 면저항과 광학적 특성을 최적화하였다. Ag 나노와이어 도전성 잉크를 코팅한 후 30초간 $O_2$ 플라즈마 처리를 하였을 때 면저항은 최대 27 % 정도 감소하였으며, 잔류 유기물의 제거를 통하여 그 광학적 특성도 향상됨을 알 수 있었다. 또한 $O_2$ 플라즈마 처리 시간이 30초 이상 증가할 경우 그 면저항이 오히려 감소함을 확인하였는데, 이는 과도한 $O_2$ 플라즈마로 인하여 Ag나노와이어의 degradation이 일어나는데 그 원인이 있음을 확인하였다.