A self-powered display— thin, flexible, and durable enough to be incorporated into clothing—is one of the goals of a $1.7 million international research project that aims to bring organic light-emitting diodes (OLEDs) to the mass market. The research consortium, known as Modecom (for Modeling Electroactive Conjugated Materials at the Multiscale), includes 13 engineering teams from nine universities and two companies.
Over the next three years, the researchers plan to improve the science behind OLEDs, making them powerful, reliable, and efficient enough to be used in an array of business and consumer products. OLEDs are already a part of some portable gadgets, such as mobile phones and MP3 players. But Modecom wants to make it practical for the devices to be used in large-screen applications, such as televisions and computer displays.
Increasing the size of OLEDs would also open the door to cutting-edge applications, like clothing-based displays, next-generation lighting systems, and portable solar power panels, explains project coordinator Alison Walker, a senior lecturer in the physics department at England's University of Bath (Fig. 1).
The biggest problem with current OLEDs is reliability. Gadget-sized OLEDs work well enough, but larger versions— designed for use in TVs and desktop displays—tend to fail quickly, often within months. Walker says the consortium is aiming for an improved understanding of how OLEDs work, which will aid in the design of longer lasting OLEDs.
"We are trying to link how they are made with how they perform, a very ambitious task but one in which we expect at least partial success," she says.
Modecom is focusing on two specific types of OLEDs: small molecule devices, developed in the U.S. and Japan by firms including DuPont subsidiary Uniax, and polymer OLEDs (P-OLEDs), pioneered in Europe by Cambridge Display Technology, a Modecom partner, Philips, and several other firms (Fig. 2).
"Small molecule OLED devices are further \[along\] in development, but are more expensive to make as they can not be made by inkjet printing," Walker says. She also predicts that large OLEDs will reach the market in less than five years.
At that point, she expects clothing vendors to weave OLED strips, running off of solar power, into garments. The strips could change color at the press of button or be used to display electronic messages. "They are cheap to make, are flexible, are bright," Walker says. "Polymers are inherently compatible with clothing, unlike their competitors in the display market such as liquid crystal displays."
Walker expects OLEDs to begin replacing incandescent, fluorescent, and even conventional LED lights within the same five years and to someday become the leading artificial lighting technology.
Walker notes that Modecom's molecular- and device-level research will also help expand the understanding of polymer materials used in plastic electronics for applications such as electronic paper and intelligent labels (Fig. 3). "OLEDs would not have advanced to their present stage, nor would have any hope of getting further, unless the science is understood," she says.