Blue organic electroluminescence of 1,3,5-triaryl-2-pyrazoline

A triaryl pyrazoline derivative was synthesized and used as a dopant in blue organic electroluminescent devices. These devices were fabricated using the basic structure of indium tin oxide (ITO)/NPB/TPBI/Mg:Ag, where NPB (N,N′-bis-(1-naphthyl)-N,N′- diphenyl-1,1′-biphenyl-4,4′-diamine) was used as a hole transport layer (HTL) and TPBI (a trimer of N-arylbenzimidazoles) as an electron transport layer (ETL). The pyrazoline derivative was doped into the hole transport layer or the electron transport layer or both. Bright blue emission from the triaryl pyrazoline was obtained from all the device configurations used. The device that had dopant in both HTL and ETL was more efficient than the devices that had dopant in either HTL or ETL. The device with 5% dopant in both HTL and ETL achieved a blue emission peaking around 470 nm and a luminance of 5500 cd/m² at a current density of about 300 mA/cm².