Paper-Thin Displays Created
Soft lithography forms wiring for thermally activated device.
Michael A. Greenwood
A group at The Hong Kong University of Science and Technology has created flexible displays as thin as paper by embedding conductive wiring patterns into thermochromic composite films.
The paperlike display fabricated with polydimethylsioxane-based thermochromic and silver nanoparticle composites provides ample flexibility.
The finished display is lightweight and flexible enough that it can be wrapped around a column and still work, said lead researcher Weijia Wen. Potential applications include smart windows, color filters, temperature sensors, advertising — even electronic books.
He said that the researchers made the thermally activated device by mixing metallic nanoparticles in polydimethylsiloxane and used soft lithography to form the conductive wiring.
They tuned the displayed color by varying the temperature in a reversible and repeatable manner.
The thickness of the display is ∼150 μm, enabling it to be easily bent or folded while its normal display functions are still maintained. The researchers said that the displays also are easy to fabricate, and they are inexpensive and use relatively little power.
The logo of Hong Kong University of Science and Technology appears when the electricity is turned on.
One drawback is that it takes at least several seconds for the display to form, making it unsuitable for applications that require rapid response times, such as television monitors. Also, if too much heat is applied to the display, the image can become blurred. To overcome this, the researchers incorporated periodic square pulsed trains with a fixed duty cycle. This technique maintained the display’s clarity and reduced its power consumption.
They plan to find interested parties so that the technology can be further developed toward specific applications.
Applied Physics Letters, May 21, 2007, Vol. 90, 213508.
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