Application of fused-heterocyclic compounds in red phosphorescent iridium(III) complexes

Organic light-emitting diodes (OLEDs) have attracted considerable attention during the last decade because of the potential advantages associated with their usage in full-color displays. Electroluminescent phosphorescent materials have also enjoyed similar levels of attention because of their excellent luminescent properties. The three primary colors, blue, green, and red, are essential for the practical application of phosphorescent complexes in flat-panel displays. Relative to the efficient green phosphorescent materials, red phosphorescent materials suffer many problems, including poor color purity, low efficiency, and low luminance, and the design of appropriate red colored materials therefore represents a significant challenge. Fused-heterocyclic compounds have been widely used in red phosphorescent iridium(III) complexes because of their high quantum efficiency, color adjustability, and balanced charge injection and migration. This review summarizes the development and application of fused-heterocyclic compounds in recent years in small molecule, dendrimer and polymeric red phosphorescent iridium(III) complexes. The influence of the molecular structures of iridium(III) complexes on the optical and electrical properties and device performances has also been described. Finally, a discussion of the prospect of developing fused-heterocyclic compounds in the red phosphorescent materials has also been provided.