Blue light-emitting materials based on terfluorenes with carbazole terminal units

Three thermally stable ter(9,9-disubstitutedfluorene)s with hole-transporting carbazole moieties at two terminals (DCTFs) have been synthesized by modified Ullmann reaction and Pd-catalyzed Suzuki coupling. The resulting compounds are amorphous with glass transition temperature (Tg) in the range of 201-205 °C. The electroluminescence efficiency up to 1.6 cd/A has been achieved with the device structure of ITO/NPB (30 nm)/DCTF-3(30 nm)/BCP (20 nm)/Alq3 (30 nm)/LiF/Al. A 60% increase of efficiency along with the CIE coordinates of (0.16, 0.11) was demonstrated compared with terfluorene (TF) analogue based device.