Engineering researchers at the University of Torontohave developed the first-ever efficient organic light-emitting diodes (OLEDs) on plastic — providing a display screen material with flexibility; and a less costly alternative to traditional OLED manufacturing, which currently relies on rigid glass.
OLEDs provide high-contrast and low-energy displays that are rapidly becoming the dominant technology for advanced electronic screens. Within five to 10 years, according to the researchers, their flexible OLEDs will be “scaled up,” for use in television screens, computer monitors, mobile phones, and PDAs,
An OLED display works without a backlight. Thus it can display deep black levels and can be thinner and lighter than liquid crystal displays (LCDs). In low ambient-light conditions, such as dark rooms, an OLED screen can achieve a higher contrast ratio than an LCD.
Current state-of-the-art OLEDs are produced using heavy-metal doped glass, which amplifies light signals, in order to achieve high efficiency and brightness—which makes them expensive to manufacture, heavy, rigid, and fragile.
"For years, the biggest excitement behind OLED technologies has been the potential to effectively produce them on flexible plastic," said Materials Science and Engineering ProfessorZheng-Hong Lu, the Canada Research Chair (Tier I) in Organic Optoelectronics. The research, which was supervised by Lu and led by Ph.D. candidates Zhibin Wang and Michael G. Helander, demonstrated the first high-efficiency OLED on plastic. The performance of their device is comparable with the best glass-based OLEDs, while providing the benefits offered by using plastic.
"This discovery unlocks the full potential of OLEDs leading the way to energy-efficient, flexible, and impact-resistant displays," said Lu.
Wang and Helander were able to re-construct the high-refractive index property previously limited to glass by using a 50-100 nanometer-thick layer of an advanced optical thin-film coating material. This advanced coating technique, when applied on flexible plastic, allowed the team to build the highest efficiency OLED device ever reported with a glass-free design.
Helander said that, eventually, he expects the flexible OLEDs to be used for lighting — maybe even incorporated into wallpaper that would light a room.
The results Wang and Helander’s work, entitled “Unlocking the Full Potential of Organic Light-Emitting Diodes (News 
- Alert) on Flexible Plastic” are published online in the latest issue of the journal Nature Photonics. A video interview with Michael G. Helander discussing this research is available here.
Cheryl Kaften is an accomplished communicator who has written for consumer and corporate audiences. She has worked extensively for MasterCard (News - Alert) Worldwide, Philip Morris USA (Altria), and KPMG, and has consulted for Estee Lauder and the Philadelphia Inquirer Newspapers. To read more of her articles, please visit her columnist page.Edited by
Rich Steeves
