Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Improving organic transistors that drive flexible and conformable electronics

06.05.2015

UMass Amherst scientists advance understanding of strain effects on performance

A revolution is coming in flexible electronic technologies as cheaper, more flexible, organic transistors come on the scene to replace expensive, rigid, silicone-based semiconductors, but not enough is known about how bending in these new thin-film electronic devices will affect their performance, say materials scientists at the University of Massachusetts Amherst.


Schematic of wrinkled rubrene single-crystal field-effect transistor. Wrinkles are obtained when in-plane compressive strain is applied on the elastomeric substrate. Electric current between gold (Au) electrodes is modulated by the deformation imposed by the wrinkles.

Credit: UMass Amherst

Writing in the current issue of Nature Communications, polymer scientists Alejandro Briseño and Alfred Crosby at UMass Amherst, with their doctoral student Marcos Reyes-Martinez, now a postdoctoral researcher at Princeton, report results of their recent investigation of how micro-scale wrinkling affects electrical performance in carbon-based, single-crystal semiconductors.

They are the first to apply inhomogeneous deformations, that is strain, to the conducting channel of an organic transistor and to understand the observed effects, says Reyes-Martinez, who conducted the series of experiments as part of his doctoral work.

As he explains, "This is relevant to today's tech industry because transistors drive the logic of all the consumer electronics we use. In the screen on your smart phone, for example, every little pixel that makes up the image is turned on and off by hundreds of thousands or even millions of miniaturized transistors."

"Traditionally, the transistors are rigid, made of an inorganic material such as silicon," he adds. "We're working with a crystalline semiconductor called rubrene, which is an organic, carbon-based material that has performance factors, such as charge-carrier mobility, surpassing those measured in amorphous silicon.

Organic semiconductors are an interesting alternative to silicon because their properties can be tuned to make them easily processed, allowing them to coat a variety of surfaces, including soft substrates at relatively low temperatures. As a result, devices based on organic semiconductors are projected to be cheaper since they do not require high temperatures, clean rooms and expensive processing steps like silicon does."

Until now, Reyes-Martinez notes, most researchers have focused on controlling the detrimental effects of mechanical deformation to a transistor's electrical properties. But in their series of systematic experiments, the UMass Amherst team discovered that mechanical deformations only decrease performance under certain conditions, and actually can enhance or have no effect in other instances.

"Our goal was not only to show these effects, but to explain and understand them. What we've done is take advantage of the ordered structure of ultra-thin organic single crystals of rubrene to fabricate high-perfomance, thin-film transistors," he says. "This is the first time that anyone has carried out detailed fundamental work at these length scales with a single crystal."

Though single crystals were once thought to be too fragile for flexible applications, the UMass Amherst team found that crystals ranging in thickness from about 150 nanometers to 1 micrometer were thin enough to be wrinkled and applied to any elastomer substrate. Reyes-Martinez also notes, "Our experiments are especially important because they help scientists working on flexible electronic devices to determine performance limitations of new materials under extreme mechanical deformations, such as when electronic devices conform to skin."

They developed an analytical model based on plate bending theory to quantify the different local strains imposed on the transistor structure by the wrinkle deformations. Using their model they are able to predict how different deformations modulate charge mobility, which no one had quantified before, Reyes-Martinez notes.

These contributions "represent a significant step forward in structure-function relationships in organic semiconductors, critical for the development of the next generation of flexible electronic devices," the authors point out.

Media Contact

Janet Lathrop
jlathrop@admin.umass.edu
413-545-0444

 @umassamherst

http://www.umass.edu 

Janet Lathrop | EurekAlert!

More articles from Materials Sciences:

nachricht Nanomaterial makes laser light more applicable
28.03.2017 | Christian-Albrechts-Universität zu Kiel

nachricht New value added to the ICSD (Inorganic Crystal Structure Database)
27.03.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Transport of molecular motors into cilia

28.03.2017 | Life Sciences

A novel hybrid UAV that may change the way people operate drones

28.03.2017 | Information Technology

NASA spacecraft investigate clues in radiation belts

28.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>