Graphene's the right stuff for organic LEDs, says Stanford team

PORTLAND, Ore. — Graphene could provide a cheaper, thinner, faster alternative to the rare and expensive indium tin oxide (ITO) universally used today for the transparent electrodes on organic LED displays, sidestepping ITO shortages and smoothing the way for development of flexible display technologies, according to Stanford University researchers.

Graphene has proved difficult to fabricate directly onto large-area substrates, but the Stanford team claimed successful demonstration of an inexpensive, solution-based spin-coating dispersion technique for fabricating transparent graphene OLED anodes.

Today's organic displays use inorganic ITO for the transparent electrodes that turn pixels on and off, but the material is costly and in short supply because it is also used in LCD flat-panel manufacture. Graphene could cut costs more than a hundredfold, according to the Stanford researchers.

They added that graphene's higher electron mobility enables electrodes that are thinner, more transparent and more conductive than ITO equivalents. Those qualities could enable development of ultrathin, flexible OLED displays.

"Our electrodes are only a few nanometers thick, which will give designers more freedom in how they design displays," said doctoral candidate Junbo Wu, who performed the work with Stanford EE professor Peter Peumans.

The researchers now are working to eliminate the vacuum annealing step they currently use to increase the conductivity of the material on quartz substrates. That would open the door to fabricating graphene electrodes at low temperatures atop flexible plastic substrates.