Preliminary communication Multilayer light emitting diodes based on columnar discotics

Abstract

Columnar discotics were used as the hole transporting layer in single layer, two layer and three layer light emitting diodes because of the unusually large hole mobility of such materials. The observations are that the onset fields are small compared with most devices using nondiscotic hole transporting layers, that these values are strongly reduced with increasing number of layers, that the orientation of the columns along the layer film normal causes a further decrease of the onset voltage and finally that the quantum efficiencies increase significantly as the number of layers is increased.