Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (09): 2529-2534.doi: 10.3866/PKU.WHXB20100831


Carrier Injection Property of Fluorene-Aromatic Nitrogen Heterocycle Copolymers

SUN Guan-Nan1, XU Hai1,2, LIU Xiao-Dong2, LIU Dan-Dan1, YANG Bing1,2, TIAN Lei-Lei1, MA Yu-Guang1   

  1. 1. State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China;
    2. College of Chemistry, Jilin University, Changchun 130012, P. R. China
  • Received:2010-03-18 Revised:2010-05-14 Published:2010-09-02
  • Contact: YANG Bing, MA Yu-Guang,
  • Supported by:

    The project was supported by the National Key Basic Research Programof China (973) (2009CB623605) and National Natural Science Foundation of China (20834006, 20774034).


To improve the carrier-injection of polyfluorene, oligomers of polyfluorene, fluorene-bipyridine, and fluorene-phenanthrolin copolymers were theoretically studied for their geometries, electronic structures, excitation energies, and reorganization energies by density functional theory at the B3LYP/6-31Glevel. We evaluated the properties of the corresponding polymers by linear extrapolation. We found a large decrease of about 0.45/0.47 eV and 0.32/0.38 eVfor the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels, respectively, after the introduction of electron-deficient bipyridine/phenanthrolin into polyfluorene. These molecules improved the electron injection ability and the balance of carrier-injection in polyfluorene systems. Additionally, the reorganization energy increased for both electron and hole transports upon the incorporation of bipyridine, which resulted in worse carrier mobility. However, the fluorene-phenanthrolin copolymer showed a similar charge transport property to polyfluorene.

Key words: Polyfluorene, Bipyridine, Phenanthrolin, Carrier-injection, Quantumchemistry


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