Characterization of orange OLED stack for bidirectional active-matrix OLED microdisplays
Highly efficient, low-voltage organic light emitting diodes (OLEDs) are well suitable for the integration into a CMOS-process. An orange emitting phosphorescent OLED-stack with doped charge transport layers was prepared on different types of CMOS substrates. First OLED deposition was done on a single diode 6"- Wafer substrate and afterwards on a micro structured two metal layer CMOS test substrate without active transistor area. The different test substrates were measured and compared with respect to their performance (current, luminance, voltage, luminance dependence on viewing angle, optical outcoupling etc.) For bidirectional microdisplay applications the dynamic characteristics of the OLED stack are also of interest. Therefore the charge and discharge behaviour and the switch on and switch off delay time of voltage apply to luminance output are measured and summarised in a simple model.