SYNTHESIS OF POLYMERS FOR HOLE AND ELECTRON-TRANSPORT MATERIALS IN ORGANIC ELECTROLUMINESCENT DEVICES

Styrene-type polymers having tetraphenylbenzidine (TPD) or tetraphenyl phenyldiaminobenzene unit (PDA) and a oxadiazole unit (PBD) on the sid e chain were prepared as hole and electron transport materials, respec tively, of an electroluminescent (EL) device. The device structures em ployed were [indium-tin-oxide (ITO)/hole transport layer (HTL)/Al] (ty pe I), or [ITO/hole transport layer (HTL)/electron transport layer (ET L)/Al] (type II). Type I devices provided current density higher than 100 mA/cm(2) but no luminescence was observed. Type II devices emitted luminescence of about 10 cd/m(2) at the current density of about 170 mA/cm(2). The emission maximums of these devices were 460 and 530 nm f or the device using TPD and PDA, respectively.