Advance in FluoreneBased Blue Electroluminescent Materials

Since the earliest reports of organic/polymeric light emitting diodes (OLEDs/PLEDs), fabricating ultrathin, full color, freeangle and largearea displays have stimulated intensive research interest around the world. To realize full color displays, high performance red, green, and blue lightemitting materials are required. In contrast to red and green emitters, only a few blue emitters showed efficient blue lightemitting materials can be used as not only emissive layer in OLEDs/PLEDs, but also host materials for efficient blue and white light source. Among the promising blue emitters, fluorenebased oligomers and polymers have displayed excellent thermal stabilities, fluorescent quantum yields, and electroluminescent behaviors. However, the fluorenebased electroluminescent blue materials usually exhibited inferior electroluminescence efficiency, poor color purity and spectral stability caused by weak charge injection and transport, aggregation/excimer formation, and/or the fluorenone of photooxidized fluorene. The progress of the fluorenebased blue lightemitting compounds and polymers was reviewed. The key point of the review was paid to the design, synthesis, and electroluminescent performance of oligofluorenes and polyfluorenes with electrondonors and/or acceptors. A large number of literatures have demonstrated that the materials containing both electrondonating and electronwithdrawing segments could have better performance than those corresponding “holeonly” or “electrononly” materials.