Electronic structure and optical properties of charged oligofluorenes studied by VIS/NIR spectroscopy and time-dependent density functional theory

被引:39
作者
Fratiloiu, S
Grozerna, FC
Koizumi, Y
Seki, S
Saeki, A
Tagawa, S
Dudek, SP
Siebbeles, LDA
机构
[1] Delft Univ Technol, Optoelect Mat Sect, DelftChemTech, NL-2629 JB Delft, Netherlands
[2] Osaka Univ, Inst Sci & Ind Res, Osaka 5670047, Japan
[3] Eindhoven Univ Technol, Lab Macromol & Organ Chem, NL-5600 MB Eindhoven, Netherlands
关键词
D O I
10.1021/jp055785f
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The electronic structure and optical properties of charged oligofluorenes were studied experimentally and theoretically. Measurements of the optical absorption spectra of charged oligofluorenes in dilute solutions have been performed by using the pulse radiolysis technique. In addition, optical absorption spectra of radical cations and anions in a solid matrix were measured after gamma-irradiation at 77 K. The optical absorption spectra were measured in the range of 440-2100 nm (0.6-2.8 eV) and compared with results from time-dependent density functional theory (TDDFT) calculations. The calculated charge induced deformations and charge distribution do not indicate the occurrence of polaronic effects. The potential energy profiles for rotation around the inter-unit bond show that oligofluorenes are nonplanar in their neutral state, while they tend to more planar structures in their charged state. The optical absorption spectra of charged oligofluorenes are dependent on the angle between neighboring units. TDDFT absorption energies shift to lower values with increasing chain length, which suggests that the charge delocalizes along the oligomer chain.
引用
收藏
页码:5984 / 5993
页数:10
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