Some applications such as active matrix display and flexible OLED may require a surface-emitting OLED structure on opaque substrates (e.g., silicon based electronics driver and pixel switching elements, stainless steel, etc). Thus, it is highly desirable to develop high performance and transparent cathodes that can be conveniently deposited on organic materials.
Ytterbium (Yb) was found to be able to prepare a highly transparent cathode by co-evaporating Yb and Ag to form a Yb:Ag alloy electrode. Surface-emitting (or top emission) and transparent (emission from both surfaces) OLEDs with low turn-on voltage (3.75 V) and high efficiency could be obtained.
