A team of scientists in Taiwan is paving the way for the development of highly-efficient phosphorescent materials, which could eventually replace the traditional incandescent lightbulb.

Organic light-emitting diodes (OLEDs) are made up of a series of organic thin films sandwiched between two conductors, which emit a bright light when an electric current is applied. Unlike liquid crystals, OLEDs actually emit light, and so wouldn't need a backlight to create a display. Francesco Barigelletti, an expert in photochemistry at the institute for organic synthesis and photoreactivity (ISOF-CNR) in Bologna, Italy, said, 'OLED technology has the potential to replace liquid crystal displays. A key development to this goal is the fabrication of cheap and flexible organic-based substrates.' 

Now researchers in Taiwan have made a range of iridium complexes that can be tuned to emit different colours of light, simply by changing one of the ligands. This is a key aim of OLED research, because the manufacture of full colour displays, for example in a television, would require OLEDs of three colours; blue, red and green.

Organic light-emitting diodes may be able to replace the traditional incandescent lightbulb

'Currently, researchers all over the world are expending their efforts in finding high quantum efficiency, true-blue or near infrared phosphorescent materials for various optoelectronic applications. We believe that our colour tuning methodology will provide guidance to address the fundamental design logics aimed at these ongoing research goals,' said team member Yun Chi, from National Tsing Hua University, Hsinchu.

Looking further ahead, emerging OLED technologies that emit white light could be used to make lighting equipment. Chi and his team are currently collaborating with the Seattle based research company Advanced Electroluminescent Sciences, who intend to incorporate the tuning technology into their OLED products for commercial and residential applications. As they use less power than traditional lightbulbs, OLEDs could be the 'green' lightbulb of the future.

May Copsey