In the last few years, industrial research into materials fulfilling the needs of the maturing OLED display industry has intensified considerably. A first generation of polymers (phenyl- PPVs) is now being commercially exploited in first monochrome polymer LED display applications. Based on these materials, non-planar displays have already been demonstrated. However, those proof of concept devices have been monochrome. Especially the RGB materials need considerable improvement to be suitable for flexible full color displays.
We will therefore report on the progress in the development of polymers for red, green, and blue emission. Our main focus here is on improving the properties of various polymers derived from the spiro-bifluorene core.
Depending on the color, the main issues vary strongly: For BLUE polymers, efficiency, color coordinates, and processibility are already at a commercial level while operational lifetime still needs strong improvement. RED materials are in an almost contrary situation: here, the operational lifetime is excellent, whereas the efficiency and the driving current are requiring further improvement. For GREEN, achieving saturated emission, whilst maintaining the other properties (high efficiency, long operational lifetime), is still challenging. We will demonstrate the current status of material development within Covion.
In addition, we achieved advances in full-color patterning, especially techniques based on Ink-Jet printing. This technology potentially allows the efficient manufacturing of high resolution RGB devices on a variety of substrates, including flexible layers.