Cheaper, more efficient OLEDs - just add chlorine
By Darren Quick
April 14, 2011
A team of researchers from the University of Toronto has developed a new technique to produce OLED devices that they say will accelerate the adoption of OLED technology into mainstream flat-panel displays and other lighting technologies. The process involves engineering a one-atom thick sheet of chlorine onto the surface of an indium tin oxide (ITO) material, which is used as a standard electrode material in today's flat panel displays. The end result is an OLED device that is not only more efficient, but also simpler and cheaper to produce.
The one-atom thick layer of chlorine is applied to the surface of ITO using a UV light assisted process that negates the need for chlorine gas, which the researcher point out makes the process safe and reliable. The resultant chlorinated ITO material allows for the efficient transport of electrons, while eliminating the need for several costly layers found in conventional OLED devices.
In tests that pitted their green-emitting "Cl-OLED" against a conventional OLED, the researchers found that the efficiency of their device was more than double that of conventional OLEDs at very high brightness. Although OLEDs are recognized for their high-efficiency, which is much greater than LCD, as the brightness is increased, the efficiency drops off dramatically. With the chlorinated ITO, the researchers were able to prevent this drop off and achieve a record efficiency of 50 percent at 10,000 cd/m2, which is more than twice as efficient as conventional OLEDs.
"Our Cl-ITO eliminates the need for several stacked layers found in traditional OLEDs, reducing the number of manufacturing steps and equipment, which ultimately cuts down on the costs associated with setting up a production line," says the University of Toronto's Professor Zheng-Hong Lu, who led the research. "This effectively lowers barriers for mass production and thereby accelerates the adoption of OLED devices into mainstream flat-panel displays and other lighting technologies," Lu added.
We can only hope he's right, because after seeing a few OLED displays at trade-shows over the past couple of years, we've been anxiously awaiting the arrival of OLED TV's that are cheaper and offer bigger screen sizes than the previous offerings from the likes of LG and Sony.