US researchers have come up with a simple surface treatment technique that may help in the mass production of large arrays of organic electronic transistors on polymer sheets for a wide range of applications-such as flexible displays, intelligent paper and flexible sheets of biosensor arrays for field diagnostics-at low cost.
London, February 20 : US researchers have come up with a simple surface treatment technique that may help in the mass production of large arrays of organic electronic transistors on polymer sheets for a wide range of applications-such as flexible displays, "intelligent paper" and flexible sheets of biosensor arrays for field diagnostics-at low cost.
A collaboration between researchers from the National Institute of Standards and Technology (NIST), the Pennsylvania State University, and the University of Kentucky led to this development.
In their study report, the researchers revealed that a chemical pre-treatment of electrical contacts can induce self-assembly of molecular crystals to improve the performance of organic semiconductor devices as well as to provide electrical isolation between devices.
Although organic electronic devices are inching towards the market, developing an efficient method to create them has been a great challenge faced by scientists to date.
Generally, large areas can be coated rapidly with a thin film of the organic compound in solution, which dries to a semiconductor layer.
But for big arrays like displays, the layer must be patterned into electrically isolated devices, and doing that requires one or more additional steps that are costly, time-consuming and/or difficult to do accurately.
The researchers studied the organic version of a workhorse device-the field effect transistor (FET)-that commonly is used as a switch to turn pixels on and off in computer displays.
According to them, the essential structure consists of two electrical contacts with a channel of semiconductor between them.
The study showed that applying a specially tailored pre-treatment compound to the contacts before applying the organic semiconductor solution might help induce the molecules in solution to self-assemble into well-ordered crystals at the contact sites.
Such structures grow outwards to join across the FET channel in a way that provides good electrical properties at the FET site, but further away from the treated contacts the molecules dry in a more random, helter-skelter arrangement that has dramatically poorer properties.
The researchers say that this effectively provides the needed electrical isolation for each device without any additional processing steps.
They believe that their work is an example of the merging of device structure and function that may enable low cost manufacturing, and an area where organic materials have important advantages.
Besides, the chemically engineered self-ordering of organic semiconductor molecules can also be used to create test structures for fundamental studies of charge transport and other important properties of a range of organic electronic systems, say the researchers.
The study has been reported in the online edition of Nature Materials.
ANI