Synthesis of new hole transport polymers based on N,N '-diphenyl-N,N '-bis(4-methylphenyl)-1,4-phenylenediamine

New hole transport polymers mere prepared by polyaddition of N,N'-diphenyl- N, N'-bis(4-methylphenyl)-1,4-phenylenediamine (PDA) with divinyl or diisop ropenyl benzene and were characterized by H-1 NMR, differential scanning ca lorimetry (DSC), UV absorption spectra and cyclic voltammetry. These polyme rs exhibit high glass transition temperatures and low oxidation potentials. Two-layer electroluminescent (EL) devices, in which the polymers were spin cast on ITO anode as the hole transport layer and aluminum tris(8-hydroxyq uilloline) (Alq) was used as the emitting layer, gave a high brightness of above 10000 ed m(-2) with an operating voltage of let a than 15 V.