Organic Light-Emitting Diodes Based on a Columnar Liquid-Crystalline Perylene Emitter

Abstract

Liquid crystalline materials possess great potential as emitters in organic light-emitting diodes (OLEDs) due to their self-assembling property, which may lead to anisotropic films and improved charge transport. Here, the key photophysical properties of the columnar liquid crystalline emitter perylene-3,4,9,10-tetracarboxylic tetraethyl ester (PTCTE) are investigated and the material is implemented into OLEDs. It is found that vacuum-deposited PTCTE films exhibit preferential horizontal orientation of the transition dipole moment. Embedding the emitter into different host materials leads to increased photoluminescence quantum yield but reduces molecular orientation compared to the neat film. OLEDs containing PTCTE doped into an exciplex-forming co-host achieve very high luminance exceeding 10 000 cd m−2 at 5.7 V, which is among the best performances of OLEDs based on columnar liquid crystalline emitters reported so far.