A highly luminescent polymer film that glows bright blue in response to electric current has been developed by scientists in China.

While many conducting polymers have been made before, this is the first to be strongly fluorescent, said Yuguang Ma of Jilin University, Changchun. Ma hopes it can be developed into a display technology, because the polymer can be deposited in patterns.

Ma and colleagues made the polymer film using a technique called electrodeposition. By applying a mild electric potential to a solution of the monomer and an electrolyte, the monomer polymerises onto the electrode surface, forming a luminescent layer.

There are two breakthroughs that give the final polymer its strong fluorescence, according to Ma. First, the team designed the monomer so that it would polymerise at a low voltage, which prevents the fluorescent side-chains from decomposing during electrodeposition. They also reduced the amount of electrolyte-based impurities that are left in the polymer after synthesis.

Yong Cao, an expert in polymer electroluminescence at the South China University of Technology in Guangzhou, said the film 'could lead to a completely new technology for realization of RGB [red, green, blue] patterns for organic/polymer full-color display, which is superior with its simplicity and low-cost over current technology'.

The next step will be to develop red and green luminescent films, said Ma. 'The performance and processing advantages of polymer LEDs make it an attractive technology for display applications,' he said. 'However, to transform polymer LEDs from a laboratory technology into a manufacturable and marketable technology requires a great deal of effort.'

James Mitchell Crow