ABSTRACT After the discovery of electroluminescent (EL) phenomenon in organic materials, there have been extensive research efforts on organic electroluminescent devices (OELDs), which are applicable for the flat panel display. So far, there have been a great number of studies for new emitting materials and device structures to achieve low driving voltage, high efficiency, full color emission, and good durability. Thermal stability is one of the most important requirements in OELDs, as the joule-heat generated during the device operation may severely relax and damage organic materials or metals. In this sense, aromatic polyimide because of their high glass transition temperatures as well as good mechanical properties and excellent chemical resistivity due to the rigid phenyl and imide moieties of its backbone is one of the best candidates as a thermally stable host polymer for OELD. One of the ways to fabricate OELDs having good thermal stability is, for example, to introduce polyimide into a hole-transporting layer(HTL) to bind a thermally unstable organic material, such as N,N’-diphenyl-N,N-di(m-tolyl)benzidine(TPD). In this article, we will review recent published results on the utilization of polyimides in OELDs as well as the use of polyimides as binder matrix polymers of HTL in OELDs, which have been carried out in this laboratory for several years.
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