Full colour RGB OLEDs on CMOS for active-matrix OLED microdisplays
Microdisplays are used in various optical devices such as headsets, viewfinders and helmet-mounted displays. The use of organic light emitting diodes (OLEDs) in a microdisplay on silicon substrate provides the opportunity of lower power consumption and higher optical performance compared to other near-to-eye display technologies. Highly efficient, low-voltage, top emitting OLEDs are well suitable for the integration into a CMOS-process. By reducing the operating voltage for the OLEDs below 5V, the costs for the CMOS process can be reduced significantly, because a standard process without high-voltage option can be used. Various OLED stacks on silicon substrate are presented, suitable for full colour (RGB) applications. Red and green emitting phosphorescent OLEDs and blue emitting fluorescent OLEDs all with doped charge transport layers were prepared on a two metal layer CMOS test substrate without active transistor area. Afterwards, the different test displays were meas ured and compared with respect to their performance (current, luminance, voltage, luminance dependence on viewing angle, optical outcoupling etc.).