中国物理B ›› 2012, Vol. 21 ›› Issue (7): 77302-077302.doi: 10.1088/1674-1056/21/7/077302

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Nonadiabatic dynamics of electron injection into organic molecules

朱丽萍, 邱宇, 童国平   

  1. Department of Physics, Zhejiang Normal University, Jinhua 321004, China
  • 收稿日期:2011-12-18 修回日期:2012-02-10 出版日期:2012-06-01 发布日期:2012-06-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 20974101 and 21174135).

Nonadiabatic dynamics of electron injection into organic molecules

Zhu Li-Ping(朱丽萍), Qiu Yu(邱宇), and Tong Guo-Ping(童国平)   

  1. Department of Physics, Zhejiang Normal University, Jinhua 321004, China
  • Received:2011-12-18 Revised:2012-02-10 Online:2012-06-01 Published:2012-06-01
  • Contact: Qiu Yu E-mail:yqiu@zjnu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 20974101 and 21174135).

摘要: We numerically investigate the injection process of electrons from metal electrodes to one-dimensional organic molecules by combining the extended Su--Schrieffer--Heeger (SSH) model with a nonadiabatic dynamics method. It is found that match between the Fermi level of electrodes and the highest occupied molecular orbital (HOMO) or the lowest unoccupied molecular orbital (LUMO) of organic molecules can be greatly affected by the length of organic chains, which has great impact on electron injection. The correlation between oligomers and electrodes is found to open more efficient channels for electron injection as compared with that in polymer/electrode structures. For oligomer/electrode structures, we show that the Schottky barrier essentially does not affect the electron injection as the electrode work function is smaller than a critical value. This means that the Schottky barrier is pinned for small work-function electrode. For polymer/electrode structures, we find that it is possible for the Fermi level of electrodes to be pinned to the polaronic level. The condition under which the Fermi level of electrodes exceeds the polaronic level of polymers is shown not always to lead to spontaneous electron transfer from electrodes to polymers.

关键词: nonadiabatic dynamics, electron injection, organic molecule

Abstract: We numerically investigate the injection process of electrons from metal electrodes to one-dimensional organic molecules by combining the extended Su--Schrieffer--Heeger (SSH) model with a nonadiabatic dynamics method. It is found that match between the Fermi level of electrodes and the highest occupied molecular orbital (HOMO) or the lowest unoccupied molecular orbital (LUMO) of organic molecules can be greatly affected by the length of organic chains, which has great impact on electron injection. The correlation between oligomers and electrodes is found to open more efficient channels for electron injection as compared with that in polymer/electrode structures. For oligomer/electrode structures, we show that the Schottky barrier essentially does not affect the electron injection as the electrode work function is smaller than a critical value. This means that the Schottky barrier is pinned for small work-function electrode. For polymer/electrode structures, we find that it is possible for the Fermi level of electrodes to be pinned to the polaronic level. The condition under which the Fermi level of electrodes exceeds the polaronic level of polymers is shown not always to lead to spontaneous electron transfer from electrodes to polymers.

Key words: nonadiabatic dynamics, electron injection, organic molecule

中图分类号:  (Electronic transport in interface structures)

  • 73.40.-c
71.38.-k (Polarons and electron-phonon interactions)