display technology

Super efficient OLEDs on flexible plastic

U. TORONTO (CAN) — New organic light-emitting diodes (OLEDs) are not only the most efficient ever made, but have an added bonus: They’re produced on plastic.

Developing OLEDs on plastic allows for more flexibility and is less costly to produce compared to traditional OLED manufacturing, which currently relies on rigid glass.

Engineering researchers at the University of Toronto describe the new technology in the latest issue of Nature Photonics.

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OLEDs provide high-contrast and low-energy displays that are rapidly becoming the dominant technology for advanced electronic screens. They are already used in some cell phone and other smaller-scale applications.

Current state-of-the-art OLEDs are produced using heavy-metal doped glass 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,” says Zheng-Hong Lu, a professor of materials science and engineering.

Using plastic can substantially reduce the cost of production, while providing designers with a more durable and flexible material to use in their products.

The research, which was supervised by Lu and led by PhD 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,” says Lu.

Wang and Helander were able to re-construct the high-refractive index property previously limited to heavy metal-doped glass by using a 50-100 nanometer-thick layer of tantalum(V) oxide (Ta2O5), 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.

More news from the University of Toronto: http://news.utoronto.ca/

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