Alps Electric Co Ltd developed a polymer OLED panel based on a printing technology and exhibited it at the company's exhibition, Alps Show 2008, which took place from Sept 25 to 26, 2008.
According to the company, the panel uses a film substrate on which a getter, in addition to the emission layer and the electrodes, is formed by printing. The getter is used to absorb water, etc.
The panel can be formed by all sorts of printing techniques such as gravure printing and inkjet printing. It is likely that gravure printing will be used when an inexpensive material is used, whereas inkjet and other printing methods will be used when an expensive material is applied only to the light emitting region.
The emission colors are yellow and white. Both types have a luminance of 100cd/m2. The luminance half-life of the yellow emission type is longer than 1,000 hours and that of the white type is longer than 300 hours. The drive voltage of both types is 7-25V.
The prototyped OLED panel is composed of a film substrate, a barrier layer, a getter layer, a cathode electrode, a polymer OLED emission layer, an anode electrode, another barrier layer and another film substrate, which are stacked in this order. The light emitted from the emission layer is released to outside from the film substrate on the anode electrode side.
The getter is arranged under the cathode electrode because the electrode has a poor sealing performance due to minute defects, the company said. The getter layer is 60μm±3μm thick. At the exhibition, the company presented a measurement result indicating that the life of the OLED panel is nearly tripled with the adoption of the getter layer.
In addition, the number of defects was reduced by improving the barrier layer, thereby reducing the variation in transmissivity, the company said.
The latest polymer OLED panel was developed in collaboration with Add-Vision Inc, according to Alps.