Synthesis and characterization of benzothiazole derivatives for blue electroluminescent devices

Two benzothiazole derivatives, 4-(benzo[d]thiazol-2-yl)-N-(4-(benzo[d]thiazol-2-yl)phenyl)-N-phenylbenzenamine (BBPA) and 4-(benzo[d]thiazol-2-yl)-N-(4-(benzo[d]thiazol-2-yl)phenyl)-N-naphthylbenzenamine (BBNA), were synthesized and characterized. Electroluminescent devices with compound BBPA or BBNA as the blue-emitting layer were fabricated. The triple-layer device, in which BBPA acted as the blue-emitter, NPB as the hole-transporting layer and TPBI as the electron-transporting layer (Device 1), showed a current efficiency of 5.24 cd/A, a power efficiency of 1.21 lm/W and an external quantum efficiency of 2.88% at a driving current density of 20 mA/cm2. The double-layer device with BBNA as the emitting layer and electron-transporting layer and NPB as the hole-transporting layer (Device 4) exhibited a maximum brightness of 1430 cd/m2 at 13 V with the CIE coordinates (0.21, 0.23).