Interfaces in Organic Electronic Devices—New Insights to Traditional Concepts

An epoch of using organic materials for electrical, electronic, and optoelectronic applications has been going on since 1977, when Chiang et al. [1] discovered a tremendous increase of 11 orders of magnitude in electrical conductivity of polymer when halogen was introduced into polyacetylene. A new nomenclature of “organic semiconductors” was therefore coined specifically for this new class of conducting materials. In the last 20 years, organic semiconductors have graduated rapidly from a topic of research interest to a material with a wide range of applications, which include polymer light-emitting diodes (PLEDs) [2,3], small-molecule-based organic light-emitting diodes (OLEDs) [4-7], organic lasers [8,9], organic transistors [10-12], solar cells [13-15], organic memory [16,17], etc.