Canadian researchers are using carbon nanotubes to make flexible organic light emitting diodes.
Organic light emitting diodes (OLED) are used in making light emitting fabrics for use in cell phones and televisions. Making flexible OLEDs has up to now been held back by the fragility of the brittle indium tin oxide layer that serves as the transparent electrode. But researchers at the Regroupement Québecois sur les Matériaux de Pointe (RQMP) have found a solution using carbon nanotubes.
“Organic light emitting diodes have in recent years emerged as a promising low cost technology for making large area flat panel displays and flexible light emitting fabrics,” said Richard Martel, professor at the Université de Montréal’s chemistry department. “By using carbon nanotubes, a highly conductive and flexible tube shaped carbon nanostructure, thin sheets a few tens of nanometres in thickness can be fabricated following a procedure akin to making paper. These sheets preserve the conductivity and flexibility of the carbon nanotubes and are thin enough to be highly transparent.”
By following the fabrication procedure they developed, the researchers succeeded in producing a high-performance OLED on this new electrode material. They have also identified the parameters that can be further optimised in order improve the performance of their design.
“In addition to their flexibility, carbon nanotube sheets exhibit a number of properties that make them an attractive alternative to transparent conducting oxides for display and lighting applications,” said Carla Aguirre, a researcher at the École Polytechnique affiliated with the Université de Montréal. “By applying the appropriate chemical treatment they can in principle be also made to replace the metal electrode in order to make OLEDs that emit light from both sides.”