1,3‐Diphenyl‐5‐(9‐phenanthryl)‐2‐pyrazoline(dpphp): an Excellent Hole‐Transport Material for Use in Organic Light‐Emitting Diodes

An excellent hole-transport material, 1,3-diphenyl-5-(9-phenanthryl)-2-pyrazoline (DPPhP) for OLEDs was studied. This compound not only offers high glass transition temperature ( T-g = 96degreesC), good film forming ability, and high HOMO energy level, but also displays excellent hole-transport property. The electroluminescent device with a simple structure of ITO / DPPhp (60 nm)/AlQ (60 nm)/LiF (0.8 nm)/Al shows an external quantum efficiency as high as 1.6%.