Chemists in Taiwan have made a high performance and stable organic LED that gives out white light.

Solid-state lighting, using either organic or inorganic based light-emitting diodes (LEDs), is revolutionising the way we generate light for everything from back-lighting on your mobile phone to traffic signals and home-lighting.

The challenge in this area is to make organic LEDs (OLEDs) that can compete with existing light sources in efficiency, stability, colour quality and operation lifetime. Ching-Fong Shu of the National Chiao Tung University, Hsinchu, and colleagues have now created a white light OLED that fulfils several of these prerequisites. They combined a blue-emitting polymer with a green-emitting polymer and a red emitter to produce their promising device.

LEDs are devices which convert electricity to light. Current passing through the device generates an excited state, which then decays to the ground state emitting a photon. Because of the increased efficiency of LEDs over conventional light sources such as incandescent light bulbs there is a potential for huge energy savings. LEDs that use organic polymers to emit the light are of particular interest because they are expected to be cheap to produce.

Looking to the future, Shu said 'The performance of our tailor-made polymer blend can be further enhanced by fine-tuning its structures and functional constituents, as well as by optimizing the device structure.'

Madelaine Chapman