• Journal of the Korean institute of surface engineering
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• v.50 no.6
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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.

• Journal of the Korean institute of surface engineering
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• v.50 no.6
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• pp.455-459
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• 2017

The development of flexible transparent electrode has been paid attention for flexible electronics. In this study, we have developed transparent electrode based on silver nanowires with improved electrical property and stability through ion-beam treatment. The energetic particles of ion-beam could sinter junctions of each silver nanowires and etch out polyvinylpyrollidone(PVP) coated on silver nanowires. The sheet resistance of silver nanowire transparent electrode was reduced by 74%, and the resistance uniformity was increased about 3 times after exposure of ion beam. Moreover, the stability at $85^{\circ}C$ of temperature and 85% of relative humidity could be also improved.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.547-547
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• 2012

As displays become larger and solar cells become cheaper, there is an increasing need for low-cost transparent electrodes. Intensive effort has been made to replace ITO (Indium Tin Oxide) based transparent electrode with cheap and flexible ones. Among those, silver nanowires have got limelight because of its great conductivity and flexibility. Even though the electric property of the Ag nanowire based transparent electrode surpassed ITO, the optical property needs to be improved (lower transmittance, higher haze). Here, we reported transparent electrode based on Ag nanowires and conducting polymer to improve optical properties. The Ag nanowires are coated onto PET films and the resulting transparent electrode film shows $200ohm/{\Box}$ resistance and > 90% optical transmittance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.416-417
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• 2007

We prepared flexible transparent conducting electrodes by spray coating of single-walled carbon nanotube (SWNT) networks on PET substrate and have demonstrated their use as transparent anodes for flexible organic light emitting diodes (OLEDs). The flexible CNT electrode produced by spray coating method shows relatively low sheet resistance ($150{\sim}220{\Omega}/sq.$) and high transmittance of ~60% even though it was prepared at room temperature. In addition, CNT electrode/PET sample exhibits little resistance change during 2000 bending cycles, demonstrated good mechanical robustness. Using transparent CNT electrode, it is readily possible to achieve performances comparable to commercial ITO-based OLEDs. This indicates that flexible CNT electrode is alternative anode materials for conventional ITO anode in flexible OLEDs.

• Ceramist
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• v.21 no.1
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• pp.12-23
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• 2018

As the flexible displays have been considered as a breakthrough to make a new electronics category, transparent electrodes have also confronted with an emerging issue, i.e., they also need to be mechanically flexible. For this to be made possible, a transparent electrode capable of withstanding large amounts of strain must be developed. Indium tin oxide (ITO) has been one of the most widely adopted transparent electrodes for displays and other transparent electronics, mainly supported by its high electrical conductivity and optical transparency. However, its brittle nature has forced the display industry to search for other alternatives. Recently, advances in nano-material researches have opened the door for various transparent conductive materials, which include carbon nanotube, graphene, Ag and Cu nanowire, and printable metal grids. Here we reviewed recently-published research works introducing flexible displays, all of which are employing the novel candidates for a conducting material.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1019-1021
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• 2008

Multilayer transparent electrodes (MTE) based on an ultrathin metal layer assisted by additional dielectric or semiconducting layers are investigated as electrodes in OLEDs including an inverted geometry. A special attention is paid to their tuning capability in injection behavior and to their potential for ultra-flexible electrodes.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.491-491
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• 2011

Transparent and flexible electronic devices that are light-weight, unbreakable, low power consumption, optically transparent, and mechanical flexible possibly have great potential in new applications of digital gadgets. Potential applications include transparent displays, heads-up display, sensor, and artificial skin. Recent reports on transparent and flexible field-effect transistors (tf-FETs) have focused on improving mechanical properties, optical transmittance, and performances. Most of tf-FET devices were fabricated with transparent oxide semiconductors which mechanical flexibility is limited. And, there have been no reports of transparent and flexible all-organic tf-FETs fabricated with organic semiconductor channel, gate dielectric, gate electrode, source/drain electrode, and encapsulation for sensor applications. We present the first demonstration of transparent, flexible all-organic sensor based on multifunctional organic FETs with organic semiconductor channel, gate dielectric, and electrodes having a capability of sensing infrared (IR) radiation and mechanical strain. The key component of our device design is to integrate the poly(vinylidene fluoride-triflouroethylene) (P(VDF-TrFE) co-polymer directly into transparent and flexible OFETs as a multi-functional dielectric layer, which has both piezoelectric and pyroelectric properties. The P(VDF-TrFE) co-polumer gate dielectric has a high sensitivity to the wavelength regime over 800 nm. In particular, wavelength variations of P(VDF-TrFE) molecules coincide with wavelength range of IR radiation from human body (7000 nm ~14000 nm) so that the devices are highly sensitive with IR radiation of human body. Devices were examined by measuring IR light response at different powers. After that, we continued to measure IR response under various bending radius. AC (alternating current) gate biasing method was used to separate the response of direct pyroelectric gate dielectric and other electrical parameters such as mobility, capacitance, and contact resistance. Experiment results demonstrate that the tf-OTFT with high sensitivity to IR radiation can be applied for IR sensors.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.121-121
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• 2018

Copper is a promising electronic material due to low cost and high electrical conductivity. However, the oxidation problem in an ambient condition makes a crucial issue in practical applications. In here, we developed a simple and cost-effective Cu patterning method on a flexible PET film by combining a solution processable Cu nanoparticle patterning and a low temperature post-processing using acetic acid treatment, laser sintering process and acid-assisted laser sintering process. Acid-assisted laser sintering processed Cu electrode showed superior characteristics in electrical, mechanical and chemical stability over other post-processing methods. Finally, the Cu electrode was applied to the flexible electronics applications such as flexible and transparent heaters and touch screen panels.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.490.1-490.1
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• 2014

The ZnO nanowire (NW)-based nanogenerators (NGs) can have rectifying current and potential generated by the coupled piezoelectric and semiconducting properties of ZnO by variety of external stimulation such as pushing, bending and stretching. So, ZnO NGs needed to enhance durability for stable properties of NGs. The durability of the metal electrodes used in the typical ZnO nanogenerators(NGs) is unstable for both electrical and mechanical stability. Indium tin oxide (ITO) is used as transparent flexible electrode but because of high cost and limited supply of indium, the fragility and lack of flexibility of ITO layers, alternatives are being sought. It is expected that carbon nanotube and Ag nanowire conductive coatings could be a prospective replacement. In this work, we demonstrated transparent flexible ZnO NGs by using CNT/Ag nanowire hybrid electrode, in which electrical and mechanical stability of top electrode has been improved. We grew vertical type ZnO NW by hydrothermal method and ZnO NW was coated with hybrid silicone coating solution as capping layer to enhance adhesion and durability of ZNW. We coated the CNT/Ag nanowire hybrid electrode by using bar coating system on a capping layer. Power generation of the ZnO NG is measured by using a picoammeter, a oscilloscope and confirmed surface condition with FE-SEM. As a results, the NGs using the CNT/Ag NW hybrid electrode show 75% transparency at wavelength 550 nm and small change of the resistance of the electrode after bending test. It will be discussed the effect of the improved flexibility of top electrode on power generation enhancement of ZnO NGs.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.2
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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.