Chlorine layer reduces OLED device complexity

By engineering a one-atom-thick sheet of chlorine onto the surface of an existing industry-standard electrode material (indium tin oxide [ITO]) found in today’s flat-panel displays, the researchers from the Department of Materials Science and Engineering at the University of Toronto have created a medium that allows for efficient electrical transport while eliminating the need for several costly layers found in traditional OLED devices.

‘It turns out that it’s remarkably easy to engineer this one-atom-thick layer of chlorine onto the surface of ITO,’ said Michael G Helander. ‘We developed a UV light-assisted process to achieve chlorination, which negates the need for chlorine gas, making the entire procedure safe and reliable.’

The team — including Zhibin Wang and project lead Prof Zheng-Hong Lu — tested their green-emitting ‘Cl-OLED’ against a conventional OLED and found that the efficiency was more than doubled at very high brightness.

‘OLEDs are known for their high efficiency,’ said Helander. ‘However, the challenge in conventional OLEDs is that as you increase the brightness, the efficiency drops off rapidly.’