Epoxy-carbazole polymeric network nanolayers for organic light-emitting devices

Abstract

We report the study of epoxy-carbazole polymeric network (ECzPN) nanolayers as a hole injection/transport layer in organic light-emitting devices. The ECzPN nanolayers were prepared by the thermal curing reaction of epoxidized cresol novolak and 3,6-diaminocarbazole in the presence of catalytic amount of triphenyl phosphine. The curing reaction was examined with Fourier transformed infrared spectroscopy, whilst the thermal stability was studied with thermogravimetric analysis. Optical absorption and emission spectroscopy were employed to investigate the optical properties of ECzPN nanolayers, whilst atomic force microscopy was used to examine the surface nanomorphology of ECzPN nanolayers. The result showed that the device performance was greatly influenced by the weight ratio of monomers, because the highest occupied molecular orbital level of ECzPN was significantly changed with the ratio. This is attributed to the ground-state complexes induced by the specific interaction (hydrogen bonding) between the lone pair electrons in amines of carbazole moieties and the hydroxyl group of ring-opened epoxide moieties.