Electron-vibrational dynamics of photoexcited polyfluorenes

被引:100
作者
Franco, I
Tretiak, S [1 ]
机构
[1] Los Alamos Natl Lab, Div Theoret, Los Alamos, NM 87545 USA
[2] Los Alamos Natl Lab, Ctr Nonlinear Studies, Los Alamos, NM 87545 USA
[3] Univ Toronto, Dept Chem, Chem Phys Theory Grp, Toronto, ON M5S 3H6, Canada
关键词
D O I
10.1021/ja0489285
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The highly polarizable pi-electron system of conjugated molecules forms the basis for their unique electronic and photophysical properties, which play an important role in numerous biological phenomena and make them important materials for technological applications. We present a theoretical investigation of the dynamics and relaxation of photoexcited states in conjugated polyfluorenes, which are promising materials for display applications. Our analysis shows that both fast (similar to20 fs) and slow (similar to1 ps) nuclear motions couple to the electronic degrees of freedom during the excited-state dynamics. Delocalized excitations dominate the absorption, whereas emission comes from localized (self-trapped) excitons. This localization is attributed to an inherent nonlinear coupling among vibronic degrees of freedom which leads to lattice and torsional distortions and results in specific signatures in spectroscopic observables. Computed vertical absorption and fluorescence frequencies as well as photoluminescence band shapes show good agreement with experiment. Finally, we demonstrate that dimerization such as spiro-linking does not affect the emission properties of molecules because the excitation becomes confined on a single chain of the composite molecule.
引用
收藏
页码:12130 / 12140
页数:11
相关论文
共 92 条
  • [21] Electron-vibrational relaxation of photoexcited polyfluorenes in the presence of chemical defects: A theoretical study
    Franco, I
    Tretiak, S
    [J]. CHEMICAL PHYSICS LETTERS, 2003, 372 (3-4) : 403 - 408
  • [22] Electroluminescence in conjugated polymers
    Friend, RH
    Gymer, RW
    Holmes, AB
    Burroughes, JH
    Marks, RN
    Taliani, C
    Bradley, DDC
    Dos Santos, DA
    Brédas, JL
    Lögdlund, M
    Salaneck, WR
    [J]. NATURE, 1999, 397 (6715) : 121 - 128
  • [23] Conjugated polymers. New materials for optoelectronic devices
    Friend, RH
    [J]. PURE AND APPLIED CHEMISTRY, 2001, 73 (03) : 425 - 430
  • [24] Adiabatic time-dependent density functional methods for excited state properties
    Furche, F
    Ahlrichs, R
    [J]. JOURNAL OF CHEMICAL PHYSICS, 2002, 117 (16) : 7433 - 7447
  • [25] Stabilized blue emission from polyfluorene-based light-emitting diodes: Elimination of fluorenone defects
    Gong, XO
    Iyer, PK
    Moses, D
    Bazan, GC
    Heeger, AJ
    Xiao, SS
    [J]. ADVANCED FUNCTIONAL MATERIALS, 2003, 13 (04) : 325 - 330
  • [26] Electronic structure of poly(9,9-dioctylfluorene) in the pristine and reduced state
    Greczynski, G
    Fahlman, M
    Salaneck, WR
    Johansson, N
    dos Santos, DA
    Dkhissi, A
    Brédas, JL
    [J]. JOURNAL OF CHEMICAL PHYSICS, 2002, 116 (04) : 1700 - 1706
  • [27] Grell M, 1998, ACTA POLYM, V49, P439, DOI 10.1002/(SICI)1521-4044(199808)49:8<439::AID-APOL439>3.0.CO
  • [28] 2-A
  • [29] Interplay of physical structure and photophysics for a liquid crystalline polyfluorene
    Grell, M
    Bradley, DDC
    Ungar, G
    Hill, J
    Whitehead, KS
    [J]. MACROMOLECULES, 1999, 32 (18) : 5810 - 5817
  • [30] High brightness and efficiency blue light-emitting polymer diodes
    Grice, AW
    Bradley, DDC
    Bernius, MT
    Inbasekaran, M
    Wu, WW
    Woo, EP
    [J]. APPLIED PHYSICS LETTERS, 1998, 73 (05) : 629 - 631