A semicrystalline composite,3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) doped N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPB),has been fabricated and characterized. An organic light-emitting diode using such a composite in hole injection exhibits the improved performance as compared with the reference device using neat NPB in hole injection. For example,at a luminance of 2000 cd/m 2 ,the former device gives a current efficiency of 2.0cd/A,higher than 1.6cd/A obtained from the latter device. Furthermore,the semicrystalline composite has been shown thermally to be more stable than the neat NPB thin film,which is useful for making organic light emitting diodes with a prolonged lifetime.
