26 Feb 2003
A new class of electroluminescent polymers could lead to low-cost color organic light-emitting diode displays.
The search for organic light-emitting diode (OLED) materials that could create low cost, easy to make color displays may have taken a step forward. A German collaboration claims to have made a multi-color (RGB) polymer OLED by spin coating, a simple fabrication process that suits mass production. (Nature 421 829)
The development relies on a new class of electroluminescent (EL) polymers that can be patterned in a similar way to photoresist materials. The research was performed by scientists from the University of Munich, the Technical University of Munich and Covion Organic Semiconductors in Frankfurt.
Detailed in last week's Nature the team describes a family of red, green and blue light emitting polymers that are soluble but can be cured under ultraviolet light to form solid polymer networks. Spin coating multiple films, one for each color, and then curing and patterning them allowed the German team to create a primitive pixelated RGB display.
Although other fabrication techniques, such as ink-jet printing, are being explored to create color polymer OLED displays, the German scientists say that their technique has some important benefits.
"We believe this to be a highly promising technology for the fabrication of true-color matrix displays with many advantages such as thermal and mechanical robustness and higher efficiency at high light levels than their non-crosslinked counterparts," report the researchers in their Nature paper. "Except for the blue-emitting material the efficiencies of the new generation of EL polymers do not reach the best state-of-the-art value quite yet, but this can certainly be achieved by optimizing the synthetic route."
Oliver Graydon is editor of Optics.org and Opto & Laser Europe magazine.