Deep Blue Organic Electroluminescent Materials Constructed from Acenaphthene Skeleton

Four luminescent materials with carbazole or triphenylamine electron donor and cyanobenzene electron receptor linked on the acenaphthene skeleton were synthesized. The single crystal structures of those molecules show intramolecular steric hindrance, which makes the donor/acceptor non coplanar with the acenaphthene skeleton, reducing the degree of conjugation and eliminating the pi-pi stacking effect between molecules. Their crystals are stabilized by a large number of C-H center dot center dot center dot pi intermolecular interactions, and only 3CzAB exists intramolecular pi-pi stacking. All four compounds have very high thermal stability, with 5% weight loss decompostion temperature(T-d,T-5%) above 343 celcius. The luminescence of these materials in PMMA thin films is in the deep-blue emission region(403-432 nm), with high photoluminescence efficiency ranging from 0.60 to 0.94 and fluorescence lifetimes ranging from 5.4 to 8.6 ns. The electroluminescence property test shows that the device of PaAB has the best performance, the maximum brightness can reach 2427 cd/m(2), the peak current efficiency, power efficiency and external quantum efficiency are 2.43 cd/A, 1.53 lm/W and 1.58% respectively, and the Commission Internationale de l'Eclairage (CIEx,y) coordinates are (0.15, 0.09), which are in the deep-blue light emission area.