Pyrazoline Dimers for Hole Transport Materials in Organic Electroluminescent Devices

Dimer structures of pyrazoline derivatives were synthesized in order to obtain stable films and applied to electroluminescent (EL) devices as hole transport material. A device structure of [indium-tin-oxide (ITO)/hole transport layer (HTL)/emitting layer (EML)/MgIn] was employed. When pyrazoline dimer (PYR-D3) and tris(8-hydroxyquinolinate)aluminum ( Alq 3 ) were used as HTL and EML, respectively, the EL device showed a maximum luminance of 12400 cd/m 2 at 11 V and a maximum luminous efficiency of 1.5 l m/W at 250 cd/m 2 . This showed that pyrazoline dimers functioned well as hole transport layers.