Substituent effects of 2,3-dicyano-5-[4-(diethylamino)styryl]-7-methyl-6H-1,4-diazepines on their use as red dopants in single-layer organic electroluminescence devices

6-Substituted 2,3-dicyano-5-[4-(diethylamino)styryl]-7-methyl-6H-1,4-diazepines were applied as red dopants in single-layer organic electroluminescence (EL) devices. EL maxima were observed at around 610 nm and the EL intensity of the 6-alkyl derivatives was higher than that of the unsubstituted variant under fixed bias voltage due to increased current density and improved ηext in the devices.