Solar Cells In OLED Displays Could Boost Mobile Device Lifetime

As OLED displays become more of a mainstream market for the smartphone industry, a group of researchers have developed a way of using its light output to harvest energy.

A team from the University of Cambridge has developed a thin-film photovoltaic cell, which can be used to capture light from an OLED screen, and use the power generated to charge a device. Led by Professor Arokia Nathan, the technology has been developed in collaboration with the London Centre for Nanotechnology at University College London and Canadian technology company Ignis Innovation.

Wasted light

Arman Ahnood, a researcher on the project, says: The idea originated in 2007, and we now have a system incorporating a solar cell and a battery. The cell is a thin film, which can be placed on the top of any display. The OLED industry is currently largest in smartphones, but there is no reason why the technology cannot move on to bigger displays, such as tablets.

Around 64% of light from an OLED display is projected back into the device itself. The solar film will sit behind the display, within the device, and capture this light. Although no testing has been done on the lifetime of the solar cell, Ahnood believes that the device will last as long as any OLED display it is integrated with.

Ahnood continues: 'We have a proof-of-concept device, which currently offers an 18% peak efficiency. However our aim is to get this up to 90% efficiency. We can do this by working with different materials, such as metal oxide semiconductors.

'The system generates around 5mW of energy, while a typical phone on standby draws 80mW. As we develop this, and as OLED technology improves its power conservation, we believe the system will be in a position to boost a device's battery life.'

Development of the system is ongoing, and the project has now transferred to Cambridge University's Centre for Advanced Photonics and Electronics.