物理化学学报 >> 2011, Vol. 27 >> Issue (07): 1640-1646.doi: 10.3866/PKU.WHXB20110718

理论与计算化学 上一篇    下一篇

局域和长程杂化密度泛函研究推拉结构有机发光分子

刘小君, 王宁, 程浩   

  1. 北京交通大学发光与光信息技术教育部重点实验室, 北京 100044
  • 收稿日期:2011-03-21 修回日期:2011-05-13 发布日期:2011-06-28
  • 通讯作者: 刘小君 E-mail:xjliu@bjtu.edu.cn
  • 基金资助:

    国家自然科学基金(21003009, 61077022), 北京交通大学(2009JBZ019-4, 2007RC078)和北京分子科学国家实验室经费资助

Local and Long-Range Hybrid Density Functional Study on an Organic Light-Emitting Molecule with Pull-Push Structure

LIU Xiao-Jun, WANG Ning, CHENG Hao   

  1. Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University, Beijing 100044, P. R. China
  • Received:2011-03-21 Revised:2011-05-13 Published:2011-06-28
  • Contact: LIU Xiao-Jun E-mail:xjliu@bjtu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21003009, 61077022), Beijing Jiaotong University, China (2009JBZ019-4, 2007RC078), and Beijing National Laboratory for Molecular Sciences, China.

摘要:

用含时密度泛函方法研究了具有推拉结构的有机发光材料3-(二氰亚甲基)-5,5-二甲基-1-(4-[9-咔唑基]-苯乙烯基)环己烯(DCDCC)的吸收和荧光光谱, 并考虑了溶剂效应. 通过与实验光谱的比较, 重点评价了包括局域和长程在内的8种交换泛函. 结果表明泛函的选择对结果的可靠性至关重要, 在密度泛函和含时密度泛函理论框架下, 包含44% Hartree Fock交换泛函的BMK杂化函数联同连续极化模型和中等大小的基组最适合研究DCDCC分子的光谱性质. 此外, 尽管DCDCC分子内电荷转移并没有强致发出双荧光, 但仍然可以用平面分子内电荷转移和扭转分子内电荷转移模型解释DCDCC激发态的结构. BMK泛函计算的结果表明DCDCC的激发态结构支持平面分子内电荷转移模型.

关键词: 长程杂化泛函, 局域杂化泛函, 含时密度泛函理论, 分子内电荷转移

Abstract:

The absorption and fluorescence spectra of 3-(dicyanomethylene)-5,5-dimethyl-1-(4-[9- carbazol]-styryl)cyclohexene (DCDCC), an organic light emitting material with pull-push structure, were investigated using a time-dependent density functional theory (TD-DFT) approach and bulk solvent effects were taken into account. The performance of eight exchange-correlation functionals including both local and long-range hybrids was assessed by comparing the calculated electron transition energies to experimental observations. It turns out that the appropriate choice of functionals is crucial to obtain an accurate value and BMK hybrids, which contain 44% Hartree Fock exchange, in the frame of DFT and TD-DFT with the polarizable continuum model and a medium sized basis set, emerges as an effective strategy for DCDCC. Moreover, the planar and twisted intramolecular charge transfer (PICT and TICT) models were used to interpret the excited state structure of DCDCC although the charge transfer character of the excited-state was not as intense as to emit obvious double fluorescence. The accurate structures were optimized by BMK and supported the PICT model.

Key words: Long-range hybrid, Local hybrid, Time-dependent density functional theory, Intramolecular charge transfer

MSC2000: 

  • O641