Researchers from Chalmers University of Technology, Sweden, have discovered a simple new tweak that could double the efficiency of organic electronics. OLED-displays, plastic-based solar cells and bioelectronics are just some of the technologies that could benefit from their new discovery, which deals with "double-doped" polymers.

The majority of our everyday electronics are based on inorganic semiconductors, such as silicon. Crucial to their function is a process called doping, which involves weaving impurities into the semiconductor to enhance its electrical conductivity. It is this that allows various components in solar cells and LED screens to work.

For organic - that is, carbon-based - semiconductors, this doping process is similarly of extreme importance. Since the discovery of electrically conducting plastics and polymers, a field for which a Nobel Prize was awarded in 2000, research and development of organic electronics has accelerated quickly. OLED-displays are one example which are already on the market, for example in the latest generation of smartphones. Other applications have not yet been fully realised, due in part to the fact that organic semiconductors have so far not been efficient enough.

Doping in organic semiconductors operates through what is known as a redox reaction. This means that a dopant molecule receives an electron from the semiconductor, increasing the electrical conductivity of the semiconductor. The more dopant molecules that the semiconductor can react with, the higher the conductivity - at least up to a certain limit, after which the conductivity decreases. Currently, the efficiency limit of doped organic semiconductors has been determined by the fact that the dopant molecules have only been able to exchange one electron each.

But now, in an article in the scientific journal Nature Materials, Professor Christian Muller and his group, together with colleagues from seven other universities demonstrate that it is possible to move two electrons to every dopant molecule.

"Through this 'double doping' process, the semiconductor can therefore become twice as effective," says David Kiefer, PhD student in the group and first author of the article.

According to Christian Muller, this innovation is not built on some great technical achievement. Instead, it is simply a case of seeing what others have not seen.

"The whole research field has been totally focused on studying materials which only allow one redox reaction per molecule. We chose to look at a different type of polymer, with lower ionisation energy. We saw that this material allowed the transfer of two electrons to the dopant molecule. It is actually very simple," says Christian Muller, Professor of Polymer Science at Chalmers University of Technology.

The discovery could allow further improvements to technologies which today are not competitive enough to make it to market. One problem is that polymers simply do not conduct current well enough, and so making the doping techniques more effective has long been a focus for achieving better polymer-based electronics. Now, this doubling of the conductivity of polymers, while using only the same amount of dopant material, over the same surface area as before, could represent the tipping point needed to allow several emerging technologies to be commercialised.

"With OLED displays, the development has come far enough that they are already on the market. But for other technologies to succeed and make it to market something extra is needed. With organic solar cells, for example, or electronic circuits built of organic material, we need the ability to dope certain components to the same extent as silicon-based electronics. Our approach is a step in the right direction," says Christian Muller.

The discovery offers fundamental knowledge and could help thousands of researchers to achieve advances in flexible electronics, bioelectronics and thermoelectricity. Christian Muller's research group themselves are researching several different applied areas, with polymer technology at the centre. Among other things, his group is looking into the development of electrically conducting textiles and organic solar cells.

Research Report: "Double Doping of Conjugated Polymers with Monomer Molecular Dopants"

Related Links
Chalmers University of Technology
All About Solar Energy at SolarDaily.com

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

NREL details great potential for floating PV systems
Golden CO (SPX) Jan 09, 2019
National Renewable Energy Laboratory (NREL) researchers estimate that installing floating solar photovoltaics on the more than 24,000 man-made U.S. reservoirs could generate about 10 percent of the nation's annual electricity production. Their findings, published in the journal Environmental Science and Technology, reveal for the first time the potential for floating PV to produce electricity in the United States. While the United States was the first to demonstrate floating PV panels - with ... read more