Coating technique ‘unlocks full potential of OLEDs on plastic’

Engineers in Canada claim to have developed the world’s most efficient organic light-emitting diodes (OLEDs) on plastic.

The team from the University of Toronto is researching an advanced coating technique that it says will significantly reduce the cost of manufacturing OLEDs — which currently rely on rigid glass — and allow the production of different-shaped devices.

‘For years, the biggest excitement behind OLED technologies has been the potential to effectively produce them on flexible plastic,’ said materials-science and engineering professor Zheng-Hong Lu, the research supervisor on the project.

‘This discovery unlocks the full potential of OLEDs, leading the way to energy-efficient, flexible and impact-resistant displays.’

OLEDs provide high-contrast and low-energy displays that are becoming widely used for advanced electronic screens. They are already used in some mobile-phone and other smaller-scale applications.

The research leaders, PhD students Zhibin Wang and Michael Helander, claim that the technique has allowed them to create the highest-efficiency OLED device ever reported with a glass-free design.

Current state-of-the-art OLEDs are produced using glass that contains heavy metals in order to achieve high efficiency and brightness. This makes them expensive to manufacture, heavy, rigid and fragile.

The researchers instead used a 50–100nm thick layer of tantalum (V) oxide (Ta2O5) — an advanced optical thin-film coating material — to achieve the highly refractive properties previously limited to heavy-metal ’doped’ glass.

The researchers believe that the performance of their device is comparable to the best glass-based OLEDs, while providing the material benefits offered by using plastic.