Triplet exciplex electroluminescence from two columnar liquid crystal perylene derivatives

Double layers and mixed single layers of two electronically complementary columnar liquid crystals show enhanced performances in light emitting diodes compared to devices made from single layers of only one of the materials. A shift from green to red electroluminescence is observed between single-material and two-material devices, assigned as resulting from triplet exciplexes in the electroluminescence of the two-material films, whereas singlet exciplex states contribute to the photoluminescence of the mixture and double layer films.