A new blue-emitting benzothiazole derivative for organic electroluminescent devices

A benzothiazole derivative (BT) with a high fluorescence quantum yield (φf=0.92) was synthesized and first used as a dopant in a blue organic electroluminescent device. TPD is N,N′-bis(3-methylphenyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine and was used as a hole-transporting material; DPBI is a dimer of N-arylbenzimidazole and was used as an electron-transporting material as well as the host for the blue-emitting dopant, BT. A device with a structure of ITO/TPD/DPBI–2% BT/DPBI/Mg–Ag was fabricated. The devices showed electroluminescence with an emission peak around 475 nm. A luminance of 1260 cd m−2 was achieved at a current density of 400 mA cm−2. The current efficiency of this device is about 0.50 cd A−1 at 5 V.