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Indexed by:期刊论文

Date of Publication:2012-09-01

Journal:DYES AND PIGMENTS

Included Journals:SCIE、EI、Scopus

Volume:94

Issue:3

Page Number:380-385

ISSN No.:0143-7208

Key Words:Fluorene; Trifluoromethylphenylene comonomer; Copolymer; Deep-blue; Spectra stability; Organic light-emitting diodes

Abstract:A group of novel fluorene-based copolymers were synthesized and characterized. The trifluoromethylphenylene unit was introduced into the copolymer backbone and its content ratio was varied from 10 mol% to 50 mol%. The electronic bandgap of the copolymer increases regularly with increasing trifluoromethylphenylene ratio. In contrast to pure polyfluorene, the deep-blue fluorescence of these copolymers is quite stable and not contaminated by the well-known green emission associated with fluorenone defects. The copolymers were used as an emitting layer to fabricate organic light-emitting diodes with a pure blue electroluminescence with a CIE coordinate y <= 0.10 obtained for most copolymers. Whilst the presence of the trifluoromethylphenylene units in the copolymers seemed unfavorable for charge injection and device current, improved spectral purity and stability in both the photoluminescence and electroluminescence were noted and ascribed to the electron-withdrawing nature of the trifluoromethylphenylene units and the enhanced anti-autoxidation ability of the fluorene rings in these copolymers. (C) 2012 Elsevier Ltd. All rights reserved.