Synthesis and hole-transporting properties of vinyl-type polynorbornenes with ethyl ester linked triarylamine side groups

Abstract

Palladium(II)-catalyzed polymerization of norbornene monomers bearing triarylamine side groups was investigated to prepare the vinyl-type polynorbornenes having hole-transporting properties. Norbornene monomers (M1-M3) with the ethyl ester linked aryldiphenylamines where the aryl group is phenyl, m-tolyl, and 1-naphthyl, respectively, were employed. The combined use of the Pd(II) catalyst supported by N-heterocyclic carbene ligand and AgSbF(6) leads to the production of soluble polynorbornenes (P1-P3). While the cyclic voltammetry measurements show the relatively low oxidational stability of polymers, the polymers exhibit the high glass transition temperature of 305-333 degrees C. The atomic force microscopy images of the thin film of P1 reveal the very smooth film surface with a roughness of 0.29 nm, indicating the good film-forming capability of polymer. When incorporated as a hole-transporting layer in Alq(3)-based electroluminescent devices, the spin-coated polymer films display hole-transporting property suitable for the proper green emission of Alq(3). Among the devices studied, the one based on 1-naphthylamine-containing P3 exhibits the highest performance in terms of luminance and external quantum efficiency. (C) 2010 Elsevier B.V. All rights reserved.