Multilayer organic LEDs based on a new dye-doped polymer

A blue dye, 1-benzqthiazoly-3-phenyl-pyrazoline (BTPP) was found to functio n as bright light emitting dye in organic electroluminescent devices. This heterocyclic compound exhibits good characteristics of blue photoluminescen ce and electroluminescence, which has emission peak at 445 nm. The thin fil ms of fluorescent dye dispersed in poly(N-vinylcarbazole) (PVK) could serve as light-emitting layers in multilayer organic LEDs. 2-(4-Biphenyl)-5-(4-t ert-butylphenyl)-1,3,4-oxadiazole (PBD) and tris-(8-hydroxyquinoline) alumi num (Alq3) were introduced into double-layer and three-layer devices respec tively. The introduction of electron transport material Alq3 enhanced the e lectron injection and luminous efficiency, as compared with double-layer de vices. Maximum brightness and luminous efficiency can be reached up to 190 cd/m(2) and 0.31 m/W, respectively.