物理化学学报 >> 2010, Vol. 26 >> Issue (04): 1075-1081.doi: 10.3866/PKU.WHXB20100402

量子化学及计算化学 上一篇    下一篇

9,9’-螺双芴的光电性能

张诚, 严妍, 陈丽涛, 马淳安   

  1. 浙江工业大学化学工程与材料学院, 绿色化学合成技术国家重点实验室培育基地, 杭州 310014
  • 收稿日期:2009-08-12 修回日期:2009-11-13 发布日期:2010-04-02
  • 通讯作者: 陈丽涛 E-mail:ltchen@zjut.edu.cn

Photoelectric Properties of 9,9’-Spirobifluorene

ZHANG Cheng, YAN Yan, CHEN Li-Tao, MA Chun-An   

  1. State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014, P. R. China
  • Received:2009-08-12 Revised:2009-11-13 Published:2010-04-02
  • Contact: CHEN Li-Tao E-mail:ltchen@zjut.edu.cn

摘要:

采用密度泛函理论(DFT)-B3LYP/6-31G(d)方法对9,9'-螺双芴低聚物[(SBF)n(n=1-4)]体系进行全优化, 得到各分子的最高占据轨道(HOMO)和最低空轨道(LUMO)能量及HOMO-LUMO能隙, 结果表明各分子整体表现出很好的共轭性质. 并在分子的阳离子和阴离子状态的优化结构基础上, 计算得到电离势(IP)、电子亲和势(EA)、空穴抽取能(HEP)、电子抽取能(EEP)和重组能等相关能量. 利用单激发组态相互作用(CIS)/3-21G方法优化得到9,9'-螺双芴单体的S1激发态的几何构型. 用含时密度泛函理论(TD-DFT)方法计算得到了分子吸收光谱和荧光光谱的相关数据. 随着聚合长度的增加, 能隙变窄, 空穴注入和电子转移的能力都相应提高, 吸收光所需能量减小, 吸收强度(f)增大, 光谱红移. 采用线性外推法, 利用低聚物分子的各种性质与聚合度n之间的关系, 得到高聚物的相应性质.为考察9位螺芴化的影响, 将(SBF)n的相关性质与母体芴的低聚物[(FL)n(n=1-4)]进行比较, 由两者的计算结果对比显示, 在芴的9位螺芴化可以提高电子和空穴的传输能力, 并同时保留芴优良的发光性质.

关键词: 密度泛函理论, 9,9'-螺双芴, 吸收光谱, 发光性质

Abstract:

9,9'-Spirobifluorene oligomers ((SBF)n(n=1-4)) were fully optimized using density functional theory (DFT) at the B3LYP/6-31G(d) level. We obtained the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) energies, and HOMO-LUMO energy gap from these DFT calculations. All molecules have good π conjugation structures. Fromthe optimized geometries of the cationic and anionic charged states, we calculated the ionization potential (IP), electron affinity (EA), hole extraction potential (HEP), electron extraction potential (EEP), and the reorganization energy. The singlet excited geometry of 9,9'-spirobifluorene was calculated using the single-excitation configuration interaction (CIS)/3-21G method. Absorption and emission spectra were obtained by employing time-dependent (TD)-DFTcalculations. Results showthat as the lengths of oligomers increase, the HOMO-LUMOenergy gaps become narrower, the hole injection and the electron transport properties improve, the lowest excitation energies decrease, the oscillator strength (f) increases, and the maximum absorption wavelengths (λmax) show a red shift. The electronic and electrochemical properties of the polymer were predicted by extrapolating the properties of the oligomers with an infinite reciprocal chain length. To investigate the influence of substituting the 9 position of the fluorene, some parameters of the parent fluorene ((FL)n(n=1-4)) were calculated for comparison. Fromthis comparison, it is obvious that spiro-functionalization at the fluorene C-9 bridge position can greatly improve the electron and hole transport properties and the excellent emission spectral quality of the fluorene is maintained.

Key words: Density functional theory, 9,9'-Spirobifluorene, Absorption spectrum, Luminescent property

MSC2000: 

  • O641