• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.149-156
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• 2017

Recently, stretchable and transparent electrodes have received great attention owing to their potential for realizing wearable electronics. Unlike the traditional transparent electrodes represented by indium tin oxide (ITO), stretchable and transparent electrodes are able to maintain their electrical and mechanical properties even under stretching stress. Lots of research efforts have been dedicated to the development of stretchable and transparent electrodes since they represent the most important engineering platform for the production of wearable electronics. Various approaches using silver nanowires, nanostructured networks, conductive polymers, and carbon-based electrodes have been explored by many world leading research groups. In this review, present and recent advances in the fabrication methods of stretchable and transparent electrodes are discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.537-546
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• 2023

Intrinsically stretchable light-emitting diodes, composed of stretchable electrodes, charge transport layers, and luminescent materials, have garnered significant interest for enhancing human well-being and advancing the field of deformable electronics. Various luminescent materials, such as perovskites and organics, have been integrated with stretchable elastomers to function as the stretchable emissive layers in these intrinsically stretchable LEDs. Stretchable conductors including Ag nanowire based percolating structures and conducting polymers have been utilized as stretchable transparent electrode. Despite this progress, their performances in terms of efficiency and stability remain challenging compared to their structurally stretchable and rigid LED counterparts. This review offers a comprehensive overview of recent advancements in intrinsically stretchable LEDs, focusing on material innovations.

• Korean Journal of Materials Research
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• v.29 no.2
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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.

• Journal of Power System Engineering
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• v.22 no.1
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• pp.64-71
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• 2018

Currently, functional patterns are formed by screen printing on stretchable films, and they are applied to wearable and stretchable devices. In this study, three types of silver paste were prepared using three polyester binders with different Tg and molecular weights in order to impart elasticity to the conductive pattern itself. Rheological properties and DSC measurements were performed for each silver paste. Then, each silver paste was screen printing and cured by an IR dryer to evaluate adhesive strength, pencil hardness, resistance and surface shape change according to strain. As a result, it was found that the silver paste using a binder with a low Tg and a high molecular weight has the smallest resistance change depending on the strain. Namely, it was found that it is most preferable to use a binder with a low Tg and a high molecular weight as the stretchable electrode.

• Vacuum Magazine
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• v.4 no.2
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• pp.15-23
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• 2017

This article reviews technical trend in research of stretchable electrodes for wearable devices, bio-integrated devices, and stretchable electronics. Stretchable electronics is new emerging class of electronics following flexible electronics. One of the most difficult challenges in the development of stretchable electronic is to realize high performance stretchable electrodes with a low resistivity and high strain failure and stretchability against severe strain of the substrate. For this reason, there are many reports on the promising stretchable electrodes including CNT, graphene, Ag nanowire, and composite materials. We outline the recent research for stretchable substrate and stretchable electrode materials to realize highly stretchable electrodes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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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.

• Applied Science and Convergence Technology
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• v.27 no.1
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• pp.5-8
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• 2018

In this paper, plasma treatment effects on a ploy(dimethyl siloxane) substrate were analyzed for the applications of stretchable silver nanowire (Ag NWs) electrodes. The oxygen plasma treated sample shows the best performance compared to nitrogen treated and untreated samples. The lowest sheet resistance and reasonable stretching capability was achieved up to 20% strain condition without open circuit fail for the oxygen plasma treated sample.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.55-61
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• 2015

Stretchable electrode materials are focused to apply to flexible device such as e-skin and wearable computer. Used as a flexible electrode, increase in electrical resistance should be minimalized under physical strain as bend, stretch and twist. Carbon black is one of candidates, for it has many advantages of low cost, simple processing, and especially reduction in resistivity with stretching. However electrical conductivity of carbon black is relatively low to be used for electrodes. Instead graphene is one of the promising electronic materials which have great electrical conductivity and flexibility. So it is expected that graphene added carbon black may be proper to be used for stretchable electrode. In this study, under stretching electrical property of graphene added carbon black composite electrode was investigated. Mechanical stretching induced cracks in electrode which means breakage of conductive path. However stretching induced aligned graphene enhanced connectivity of carbon fillers and maintained conductive network. Above all, electronic structure of carbon electrode was changed to conduct electrons effectively under stretching by adding graphene. In conclusion, an addition of graphene gives potential of carbon black composite as a stretchable electrode.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.77-82
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• 2014

Stretchable electrodes are focused due to many demands for soft electronics. One of the candidates, carbon black composites have advantages of low cost, easy processing and decreasing resistivity in a certain range during stretching. However, the electrical conductivity of carbon black composites is not enough for electronic devices. Graphene is 2-dimensional nanostructured carbon based material which shows good electrical properties and flexibility. They may help to improve electrical conductivity of the carbon black composites. In this study, graphene was added to a carbon black electrode to enhance electrical properties and investigated. Electrical resistivity of graphene added carbon electrode decreased comparing with that of carbon black electrode because graphene bridged non-contacting carbon black aggregates to strengthen the conductive network. Also graphene reduced an increase in the resistance of the carbon black electrode applied to strain because they connected gap of separated carbon black aggregates and aligned along the stretching direction at the same time. In conclusion, an addition of graphene to carbon black gives two benefits on the electrical properties of carbon black composite as a stretchable electrode.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.7-14
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• 2015

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. Among them, Ag nanowires are particularly interesting to synthesize because bulk Ag exhibits the highest electrical conductivity among all metals. Here we reviewed recently-published research works introducing various devices from organic light emitting diode to tactile sensing devices, all of which are employing AgNW for a conducting material. They proposed methods to enhance the stretchability and reversibility of the transparent electrodes, and apply them to make various flexible and stretchable electronics. It is expected that Ag nanowires are applicable to a wide range of high-performance, low-cost, stretchable electronic devices.