World Industrial Reporter: Swedish Scientists Enable High-Precision Control of Printed Electronics

6 July, 2017 - 08:45

Researchers from Sweden’s Linköping University have printed electronic transistor circuits and displays, in which the colour of individual pixels can be changed.

According to the researchers from the Linköping’s Laboratory of Organic Electronics, this breakthrough was made possible with the conducting polymer PEDOT:PSS.

The polymer conducts both electrons and ions. Displays and transistors manufactured from this polymer have many advantages, which include that they are simple and cheap to manufacture, and the material itself is non-hazardous.

It has however been difficult to create devices that switch rapidly at a specific voltage, known as the ‘threshold voltage.’ It is difficult to control the current state of the transistors or the color state of the displays in a precise manner.

“The lack of any threshold in the redox-switching characteristics of PEDOT:PSS hampers bistability and rectification, characteristics that would allow for passive matrix addressing in display or memory functionality” says Simone Fabiano, senior lecturer at the Laboratory of Organic Electronics, LOE, who is the principal author of the article in Science Advances, together with Negar Sani from the research institute RISE Acreo.

More than five years ago, the researchers toyed with the idea of solving this problem by combining electrochemistry with ferroelectricity. Ferroelectric materials consist of dipoles. One end of a dipole has a positive charge and the other a negative charge, and these “ferroelectric” dipoles rotate when they are exposed to an electric field beyond a specific threshold.

Head of the laboratory Professor Magnus Berggren couldn’t let this idea rest, and when he was awarded a research grant from the Knut and Alice Wallenberg Foundation in December 2012 to use freely, this was one of the high-risk projects he chose to invest in.

After many years of tenacious experiments, Simone Fabiano and his colleagues at the Laboratory of Organic Electronics have managed to apply a thin layer of a ferroelectric material onto one electrode in organic electrochemical devices and circuits.

“The thickness of the layer determines the voltage at which the circuit switches or the display changes colour. Transistors are no longer required in the displays: we can control them pixel-by-pixel simply through a thin ferroelectric layer on the electrode,” says Simone Fabiano.

Read the article at World Industrial Reporter


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Printed and Organic Electronics at RISE Acreo