Organic light-emitting diode (OLED) technology is used in a variety of display applications, ranging from cell phones and MP3 to prototype TVs, and holds great promise for the production of highly efficient large-area light sources and flat panel displays. It has the potential to become a multibillion-dollar industry within a few years. The biggest technical challenge for OLEDs is the limited lifetime associated with elevated temperatures and exposure to moisture. The guaranteed hours of operation (15,000 hr) is currently inadequate for most TVs and replacement of LCDs with the 60,000 hr half-life. This book, therefore, investigated the thermal-activated and moisture-induced degradation pathways of small molecule - based prototype OLEDs as well as interfacial electronic properties at the nanoscale level through real-time visualization. The results should help shed some lights on improving luminescence efficiency and lifetime of OLEDs, and should be especially useful to professionals in research and development of not only OLED technology but other organic electronics, or anyone else who may be interested in plastic electronics.