Web Release Date: October 16,
Norbornene-Based Copolymers with Iridium Complexes and Bis(carbazolyl)fluorene Groups in Their Side-Chains and Their Use in Light-Emitting Diodes
and
School of Chemistry and Biochemistry, School of Electrical and Computer Engineering, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332
Received July 1, 2007
Revised Manuscript Received August 17, 2007
Abstract:
Solution-processable copolymers with pendant phosphorescent iridium complexes and 2,7-di(carbazol-9-yl)fluorene-type host moieties were synthesized using ruthenium-catalyzed ring-opening metathesis polymerization. Low polydispersity indices and molecular weights around 20 000 Da were obtained for all copolymers. As a result of the living character of the polymerization of the monomer containing the host moiety, a high degree of control over the molecular weights of all copolymers can be obtained. The photo- and electroluminescence properties of the copolymers were investigated. All copolymers retained the photo- and electrophysical properties of the corresponding nonpolymeric iridium complexes. Furthermore, as a proof of principle for the potential use of these materials, organic light-emitting devices were fabricated using the orange-emitting copolymer. A maximum external quantum efficiency of 1.9% at 100 cd/m2 and a turn-on voltage of 3.7 V were obtained with photoluminescence quantum yield of 0.10 demonstrating the potential of these copolymers as emissive materials for display and lighting applications.
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