Unbreakable and flexible phone is on the edge...

Breakthrough research at RMIT University is advancing transparent bendable electronics, bringing science fiction gadgets – such as unbreakable rubber-like phones, rollable tablets and even functional clothing – closer to real life.

Researchers from RMIT’s Functional Materials and Microsystems research group have developed a new method to transfer electronics with versatile functionality, which are usually made on rigid silicon, onto a flexible surface.

The result of their work is published today (13 September) in Nature Publishing Group’s Asia Materials, the leading materials science journal for the Asia-Pacific.

The ability of micro and nano-electronic devices to sense, insulate or generate energy is controlled by thin, transparent nanolayers of oxide materials, often much thinner than 1/100th of a human hair.

These oxide materials are brittle and their high processing temperatures – often in excess of 300 °C – have until now prevented their incorporation in flexible electronic devices.

Lead author, PhD researcher Philipp Gutruf, said the new process developed at RMIT could unleash the potential of fully functional flexible electronics, while providing a new way for the materials to mesh together.

"We have discovered a micro-tectonic effect, where microscale plates of oxide materials slide over each other, like geological plates, to relieve stress and retain electrical conductivity," he said.

"The novel method we have developed overcomes the challenges of incorporating oxide materials in bendable electronic devices, paving the way for bendable consumer electronics and other exciting applications."

Supervisor and co-leader of the research group, Dr Madhu Bhaskaran, said the new approach used two popular materials – transparent conductive indium tin oxide and rubber-like silicone which is also biocompatible.

“The ability to combine any functional oxide with this biocompatible material creates the potential for biomedical devices to monitor or stimulate nerve cells and organs. This is in addition to the immediate potential for consumer electronics applications in flexible displays, solar cells, and energy harvesters.”

Mr Gutruf is supported by an Australian Government Endeavour International Postgraduate Research Scholarship and the research was supported by Australian Post-Doctoral Fellowships from the Australian Research Council to Dr Bhaskaran and Dr Sharath Sriram, co-leader of the research group.

Source: http://www.rmit.edu.au/browse;ID=2p5rc967irk1;STATUS=A

Reference: http://www.nature.com/am/journal/v5/n9/full/am201341a.html

Shining a little light changes metal into semiconductor

Shining a little light changes metal into semiconductor 

          

By blending their expertise, two materials science engineers at Washington University in St. Louis changed the electronic properties of a new class of materials — just by exposing it to light.

With funding from the Washington University International Center for Advanced Renewable Energy and Sustainability (I-CARES), Parag Banerjee, PhD, and Srikanth Singamaneni, PhD, both assistant professors of materials science, brought together their respective areas of research.

Singamaneni’s area of expertise is in making tiny, pebble-like nanoparticles, particularly gold nanorods. Banerjee’s area of expertise is making thin films. They wanted to see how the properties of both materials would change when combined.

The research was published online in August in ACS Applied Materials & Interfaces.

The research team took the gold nanorods and put a very thin blanket of zinc oxide, a common ingredient in sunscreen, on top to create a composite. When they turned on light, they noticed that the composite had changed from one with metallic properties into a semiconductor, a material that partly conducts current. Semiconductors are commonly made of silicon and are used in computers and nearly all electronic devices.

“We call it metal-to-semiconductor switching,” Banerjee said. “This is a very exciting result because it can lead to opportunities in different kinds of sensors and devices.”

Banjeree said when the metallic gold nanorods are exposed to light, the electrons inside the gold get excited and enter the zinc oxide film, which is a semiconductor. When the zinc oxide gets these new electrons, it starts to conduct electricity.

“We found out that the thinner the film, the better the response,” he said. “The thicker the film, the response goes away. How thin? About 10 nanometers, or a 10 billionth of a meter.”

Other researchers working with solar cells or photovoltaic devices have noticed an improvement in performance when these two materials are combined; however, until now, none have broken it down to discover how it happens, Banerjee said.

“If we start understanding the mechanism for charge conduction, we can start thinking about applications,” he said. “We think there are opportunities to make very sensitive sensors, such as an electronic eye. We are now looking to see if there is a different response when we shine a red, blue or green light on this material.”

Banerjee also said this same technology can be used in solar cells.

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Source:  Wu F, Tian L, Kanjolia R, Singamaneni S, Banerjee P. Plasmonic Metal-to-Semiconductor Switching in Au Nanorod-ZnO nanocomposite films. ACS Applied Materials & Interfaces. Dx.doi.org/10.1021/am402309x.