Liquid crystalline materials possessgreat potential as emitters inorganic light-emitting diodes (OLEDs) due to their self-assembling property,which may lead to anisotropic films and improved charge transport. Here, weinvestigate key photophysical properties of the columnar liquid crystallineemitter perylene-3,4,9,10-tetracarboxylic tetraethyl ester (PTCTE) and implementthe material into OLEDs. We find that vacuum-deposited PTCTE films exhibitpreferential horizontal orientation of the transition dipole moment. Embeddingthe emitter into different host materials leads to increased photoluminescencequantum yield but reduces molecular orientation compared to the neat film.OLEDs containing PTCTE doped into an exciplex-forming co-host achieve very highluminance exceeding 10,000 cd m-2 at 5.7 V, which isamongst the best performance of OLEDs based on columnar liquid crystallineemitters reported so far.