A new phosphorescent iridium-amidinate complex is among a number of similar metallic compounds at the centre of the latest organic light-emitting diodes (OLEDs).

The manufacturing of OLEDs is particularly tough and expensive and the phosphorescent variety are normally fabricated through a process known as 'doping', Azonano.com reports.

This involves adding a pre-determined concentration of the complexes to a host matrix and if the concentration is too high, they cancel out each other's phosphorescent qualities.

However, a team of scientists from the RIKEN Advanced Science Institute in Wako, Japan, have discovered a novel technique which banishes the dependence on specific doping limits.

The researchers, led by Zhaomin Hou, found that they could produce OLEDs with differing doping concentrations by using aminidates to stop the cancelling out involved in an iridium complex.

As a result, they noted that prototype OLEDs produced in this way offered a bright yellow-green emission, while also using a minimal voltage in the process.

Detailing his experiments in the journal Chemical Communications, Mr Hou explained that, for the first time, the devices could now be manufactured using doping concentrations of between seven and 100 per cent.

He wrote: "One of the research projects in my group led to an efficient synthesis of various amidinates.

"We envisioned that a geometrically hindered amidinate group might overcome the problems encountered previously in phosphorescent metal complexes."

The discovery means that iridium-amidinate complexes should play an important role in the design of flat-panel screens and organic lighting, Mr Hou added.

Iridium is the second-densest element and is also the most corrosion-resistant metal.

Source:

New Phosphorescent Complexes Improve Manufacturing of High-Efficiency Light Sources (05/06/09)

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