MMaterialsgateNEWS 2013/06/03

Related MaterialsgateCARDS

Korean researchers demonstrate a new class of transparent, stretchable electrodes

Ulsan National Institute of Science & Technology (UNIST) has demonstrated that a live rabbit could wear contact lenses fitted with inorganic light-emitting diode with no side effects. This new class of hybrid transparent and stretchable electrode paves the way for flexible displays, solar cells, and electronics.

UNIST scientists have combined graphene with silver nanowires to form a thin, transparent and stretchable electrode which overcome the weaknesses of each individual material, resulting in a new class of electrodes with widespread possible applications including picture taking and scanning using soft contact lenses.

Transparent electrodes have been widely used in things like touch screens, flat-screen TVs, solar cells and light-emitting devices. Commonly made from indium tin oxide(ITO), it is brittle and cracks thus losing functionality if flexed. It also degrades over time, and is expensive due to the limited quantities of indium metal.

As an alternative, the networks of randomly distributed mNWs have been considered as promising candidates for next-generation transparent electrodes, due to their low-cost, high-speed fabrication of transparent electrodes. However, the number of disadvantages of the mNW networks limited their integration into commercial devices. They have low breakdown voltage, typically high NW-NW junction resistance, high contact resistance between network and active materials, material instability and poor adhesion to plastic substrates.

Graphene is also well known as good a candidate for transparent electrode because of their unique electrical properties and high mechanical flexibility. However, scalable graphene synthesis methods for commercialization produces lower quality graphene with individual segments called grains which increases the electrical resistance at boundaries between these grains.

Silver nanowires, on the other hand, have high resistance because they are randomly oriented like a jumble of toothpicks facing in different directions. In this random orientation, there are many contact between nanowires, resulting in high resistance due to large junction resistance of nanowires. Due to these drawbacks, neither is good for conducting electricity, but a hybrid structure, combined from two materials, is.

The hybrid material presents a high electrical and optical performance with mechanical flexibility and stretchability for flexible electronics. The hybrid transparent electrode has a low “sheet resistance” and high transmittance. There’s almost no change in its resistance when bent and folded. Where the ITO is bent, its resistance increases significantly. Additionally the hybrid material preserve its electrical and optical properties against thermal oxidation condition

The graphene-mNW hybrid structure developed by the UNIST research team is a new class of electrodes and may soon find use in a variety of other applications. The research team demonstrated Inorganic light-emitting diode (ILED) devices fitted on a soft eye contact lens using the transparent, stretchable interconnects of the hybrid electrodes as an application example.

As an in vivo study, this contact lens was worn by a live rabbit eye for five hours and no abnormal behavior, such as bloodshot eye or the rubbing of eye areas were observed in the live rabbit. Wearing eye contact lenses, picture-taking and scanning, is not science fiction anymore.

The research was led by Jang-Ung Park, professor of the School of Nano-Bioscience and Chemical Engineering at UNIST. “We believe the hybridization between two-dimensional and one-dimensional nanomaterials presents a promising strategy toward flexible, wearable electronics and implantable biosensor devices, and indicate the substantial promise of future electronics,” said Prof. Park.

Source: Ulsan National Institute of Science and Technology (UNIST), via ResearchSEA – 30.05.2013.

Investigated and edited by:

Dr.-Ing. Christoph Konetschny, Inhaber und Gründer von Materialsgate
Büro für Material- und Technologieberatung
The investigation and editing of this document was performed with best care and attention.
For the accuracy, validity, availability and applicability of the given information, we take no liability.
Please discuss the suitability concerning your specific application with the experts of the named company or organization.

You want additional material or technology investigations concerning this subject?

Materialsgate is leading in material consulting and material investigation.
Feel free to use our established consulting services

MMore on this topic

Researchers have created a new type of transparent electrode that might find uses in solar cells, flexible displays for computers and consumer electronics and future "optoelectronic" circuits for sensors and information processing.

The electrode is made of silver nanowires covered with a material called graphene, an extremely thin layer of carbon. The hybrid material shows promise as a possible replacement for indium tin oxide, or ITO, used in transparent electrodes for touch-screen monitors, cell-phone displays and flat-screen televisions. Industry is seeking alternatives to ITO because of drawbacks: It is relatively expensive due to limited abundance of indium, and it is inflexible and degrades over time, becoming brittle and hindering performance. "If you try to bend ITO it cracks and then stops functioning properly," said Purdue University doctoral student Suprem Das. The hybrid material could represent... more read more

Imagine owning a television with the thickness and weight of a sheet of paper. It will be possible, someday, thanks to the growing industry of printed electronics.

The process, which allows manufacturers to literally print or roll materials onto surfaces to produce an electronically functional device, is already used in organic solar cells and organic light-emitting diodes (OLEDs) that form the displays of cellphones. Although this emerging technology is expected to grow by tens of billions of dollars over the next 10 years, one challenge is in manufacturing at low cost in ambient conditions. In order to create light or energy by injecting or collecting electrons, printed electronics require conductors, usually calcium, magnesium or lithium, with a low-work function. These metals are chemically very reactive. They oxidize and stop working if exposed... more read more

Individual molecules have been used to create electrical components like resistors, transistors and diodes, that mimic the properties of familiar semiconductors. But according to Nongjian (NJ) Tao, a researcher at the Biodesign Institute® at Arizona State University, unique properties inherent in single molecules may also allow clever designers to produce novel devices whose behavior falls outside the performance observed in conventional electronics.

In research appearing in today's issue of Nature Nanotechnology, Tao describes a method for mechanically controlling the geometry of a single molecule, situated in a junction between a pair of gold electrodes that form a simple circuit. The manipulations produced over tenfold increase in conductivity. The unusual, often non-intuitive characteristics of single molecules may eventually be introduced into a broad range of microelectronics, suitable for applications including biological and chemical sensing; electronic and mechanical devices. Delicate molecular manipulations requiring patience and finesse are routine for Tao, whose research at Biodesign's Center for Bioelectronics... more read more


Partner of the Week

Search in MaterialsgateNEWS

Books and products