Formation dynamics of bipolaron in a metal/polymer/metal structure |
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Authors: | Y H?Yan Z?An Email author" target="_blank">C Q?WuEmail author K?Nasu |
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Institution: | (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 |
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Abstract: | 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 (t′), such as V0=0.79 eV and t′=1 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. |
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Keywords: | |
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