Acta Chimica Sinica ›› 2010, Vol. 68 ›› Issue (21): 2167-2174. Previous Articles     Next Articles

Full Papers

给、吸电子基团封端对低聚9,9 -螺双芴光电性质的改进

陈丽涛,严妍,张诚*,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)
  • 投稿日期:2010-02-08 修回日期:2010-06-01 发布日期:2010-06-22
  • 通讯作者: 严妍 E-mail:yanyan367@yahoo.com.cn
  • 基金资助:

    教育部新世纪人才计划;浙江省自然科学基金资助项目;浙江省重大科技专项和优先主题

Evident Improvements in the Photoelectronic Properties of Oligo-9,9 - Spirobifluorene Made by Donor and Acceptor End-Capping Groups

CHEN Li-Tao, YAN Yan, ZHANG Cheng, 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)
  • Received:2010-02-08 Revised:2010-06-01 Published:2010-06-22

Symmetrical and asymmetrical end capped 9,9 -spirobifluorene with electron donor or/and acceptor groups are calculated to investigate the influence of the end-capping groups by using DFT/B3LYP method at 6-31G(d) level. We fully optimize all the structures concerned. Analyzing the HOMO and LUMO energy levels and HOMO-LUMO gaps of all species, we find that the LUMO level drops while the HOMO level slightly increases and therefore the HOMO-LUMO gap shrinks when 9,9 -spirobifluorene is asymmetrically end-capped by an electron donor group oxadiazole (O) and an electron acceptor group thiophene (T). Full optimizations, at the same B3LYP/6-31G(d) level, on the structures of the oligo-9,9 -spirobifluorene end-capped with thiophene and oxadiazole [T(SBF)nO, n=1~4] show that the ratio of the partial charge of the donor group over that of the acceptor group grows larger with increasing chain length n. The donor and acceptor moieties exhibit intramolecular charge transfer (ICT) and the charge transfer gets enhanced in oligomers. The ionization potentials (IPs), electron affinities (EAs), hole extraction potentials (HEP), electron extraction potentials (EEP) and the reorganization energies (l) are calculated to show that the charge carrier injection from donor to acceptor group further facilitates the transport of both electrons and holes. Absorption spectra of T(SBF)nO (n=1~4) are obtained by employing TD-DFT and ZINDO calculations. The results show that, with increasing chain length n, the excitation energy becomes smaller, the spectra are red-shifted, and the oscillator strength is enhanced. The singlet excited geometry of T(SBF)1O is calculated using the single-excitation configuration interaction CIS method at the same 6-31G(d) level. Compared to the ground state, the excited state tends to move toward a planar geometry.

Key words: 9,9-spirobifluorene, thiophene, oxadiazole, density functional theory, end-cap