Multi-layer printing of OLEDs as a tool for the creation of security features

The combined deposition of structured and homogenous layers for the device setup of OLEDs results in a structured display visible with a gray scale impression. These permanently imprinted structures are only visible during the application of an electrical field and almost invisible in the off state. Most intriguing applications of such devices are security marks, electronic watermarks but also for advertising and design applications the creation of gray scale structures might have interesting applications.