Polymer OLEDs (PLED) are less expensive to manufacture than small-molecule OLEDs (SMOLED) and can be printed onto flexible substrates such as plastic, but are limited in their pixel pitch.

RGB Liquids from CDT

In 1989, at the Cavendish Laboratory of Cambridge University, scientists developed a polymer which emitted light when an electric current was applied. In 1992, Cambridge Display Technologies was founded by Cambridge University to further develop this technology dubbed Polymer LED, or PLED.

The polymers are water soluble, and thus existing ink-jet printing processes and equipment can be used to deposit the emissive materials. This greatly reduces the manufacturing costs of PLED displays when compared to SMOLEDs. These processes, however, are not as accurate as vacuum deposition, resulting in a maximum pixel density around 200ppi.

Since the ink-jet printing process does not require super-heating, the polymer materials can be deposited on thin film substrates such as plastic. This opens wide the possibility of both flexible and wearable PLED displays.