Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (05): 869-875.doi: 10.3866/PKU.WHXB20090517

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Ground, Excited Structures and Photoelectronic Properties of Poly(p-phenylenevinylene) Oligomers with Biphenyl Bridge

XU Hai, HE Feng, YANG Bing, ZHANG Hou-Yu, LIU Sui-Jun, GU Xin, LIU Dan-Dan, LIU Xiao-Dong, YU Jing-Sheng, MA Yu-Guang   

  1. State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China; College of Chemistry, Jilin University, Changchun 130012, P. R. China
  • Received:2009-01-09 Revised:2009-02-11 Published:2009-05-04
  • Contact: YANG Bing MA Yu-Guang;


Ground and excited state structures of several poly(p-phenylenevinylene) (PPV) oligomers that contain a biphenyl bridge were fully optimized by density functional theory (DFT) and the configuration interaction singles (CIS) method, respectively. The most rational geometric structures for the ground state, the excited state and frontier molecular orbitals were obtained. The absorption and emission properties of the oligomers were then calculated using the semi-empirical Zerner's intermediate neglect of differential overlap (ZINDO) and time-dependent density functional theory (TD-DFT). We analyzed the effect of an increase in the biphenyl chain length on frontier molecular orbitals and the energy gap. Results indicate that absorption and emission properties hardly change as the length of the biphenyl chain increases. A cross configuration between neighboring PPV oligomer chains and the degree of intrachain twist becomes increasingly obvious. Molecular symmetry is reduced and the π-π stacking effect is weakened among these types of conjugated molecules in a solid. This is perhaps the most important factor for an increase in the fluorescence quantumefficiency of light-emitting diodes.

Key words: PPV oligomer, Ground state, Excited state, Photoelectronic property


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