https://doi.org/10.1140/epjb/e2006-00009-1
Formation dynamics of bipolaron in a metal/polymer/metal structure
1
Department of Physics, Fudan University, Shanghai 200433, P.R. China
2
College of Physics, Hebei Normal University, Shijiazhuang 050016, P.R. China
3
Institute for Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801, Japan
Corresponding author: a cqw@fudan.edu.cn
Received:
25
June
2005
Published online:
19
January
2006
Charge injection process from metal electrode to a
nondegenerate polymer in a metal/ polymer/ metal structure has been
investigated by using a nonadiabatic dynamic method. We
demonstrate that the dynamical formation of a bipolaron
sensitively depends on the strength of applied electric field, the
work function of metal electrode, and the contact between the
polymer and the electrode. For a given bias applied to one of the
electrode (V0) and coupling between the electrode and the
polymer (
), such as 
eV and 
eV,
the charge injection process depending on the electric field can
be divided into the following three cases: (1) in the absence of
the electric field, only one electron tunnels into the polymer to
form a polaron near the middle of the polymer chain; (2) at low
electric fields, two electrons transfer into the polymer chain to
form a bipolaron; (3) at higher electric fields, bipolaron can not
be formed in the polymer chain, electrons are transferred from the
left electrode to right electrode through the polymer one by one
accompanying with small irregular lattice deformations.
PACS: 73.40.Ns – Metal-nonmetal contacts / 71.38.Mx – Bipolarons / 72.80.Le – Polymers; organic compounds (including organic semiconductors)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2006
