Enhanced ultraviolet emission from ZnO nanocrystals embedded in a hybrid polymer composite layer

Abstract

Self-assembled ZnO nanocrystals embedded in a p-phenylene-biphenyltetracarboximide (BPDA-PDA)-type polyimide (PI) layer or in a hybrid (BPDA-PDA) PI and poly-N-vinylcarbazole (PVK) matrix were formed by curing Zn thin films in a nitrogen atmosphere. Transmission electron microscopy images showed that ZnO nanocrystals were formed inside in the hybrid BPDA-PDA PI and PVK matrix. Photoluminescence (PL) spectra for the ZnO nanocrystals embedded in the BPDA-PDA PI layer and for the ZnO nanocrystals embedded in the hybrid polymer layer showed that addition of PVK significantly increased the luminescence intensity corresponding to the ultraviolet (UV) emission from the ZnO nanocrystals. The luminescence mechanisms related to the green and the UV bands for the ZnO nanocrystals embedded in the BPDA-PDA PI and PVK hybrid layer are described on the basis of the PL results.