Monitoring the Channel Formation in Organic Field-Effect Transistors via Photoinduced Charge Transfer

Authors

  • Thokchom Birendra Singh,

    Corresponding author
    1. Linz Institute of Organic Solar Cells (LIOS) Institute of Physical Chemistry Johannes Kepler University, Linz A 4040 (Austria)
    2. Current address: Molecular and Health Technologies, CSIRO, Ian Wark Laboratory, Bayview Ave., Clayton, VIC 3168 (Australia)
    • Linz Institute of Organic Solar Cells (LIOS) Institute of Physical Chemistry Johannes Kepler University, Linz A 4040 (Austria).
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  • Robert Koeppe,

    1. Linz Institute of Organic Solar Cells (LIOS) Institute of Physical Chemistry Johannes Kepler University, Linz A 4040 (Austria)
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  • Niyazi Serdar Sariciftci,

    1. Linz Institute of Organic Solar Cells (LIOS) Institute of Physical Chemistry Johannes Kepler University, Linz A 4040 (Austria)
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  • Mauro Morana,

    1. Konarka Technologies, Altenbergerstrasse 69 Linz A 4040 (Austria)
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  • Christoph J. Brabec

    1. Konarka Technologies, Altenbergerstrasse 69 Linz A 4040 (Austria)
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Abstract

Conducting channel formation in organic field-effect transistors (OFETs) is considered to happen in the organic semiconductor layer very close to the interface with the gate dielectric. In the gradual channel approximation, the local density of accumulated charge carriers varies as a result of applied gate bias, with the majority of the charge carriers being localized in the first few semiconductor monolayers close to the dielectric interface. In this report, a new concept is employed which enables the accumulation of charge carriers in the channel by photoinduced charge transfer. An OFET employing C60 as a semiconductor and divinyltetramethyldisiloxane-bis(benzocyclobutene) as the gate dielectric is modified by a very thin noncontinuous layer of zinc-phthalocyanine (ZnPc) at the semiconductor/dielectric interface. With this device geometry, it is possible to excite the phthalocyanine selectively and photogenerate charges directly at the semiconductor/dielectric interface via photoinduced electron transfer from ZnPc onto C60. Thus the formation of a gate induced and a photoinduced channel in the same device can be correlated.

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