Helena Alves,

INESC MN –

Abstract:

The investigation of material systems in which new electronic phenomena arise from the
interactions of molecules, is an active topic of research. In particular, electrical transport at the
surface of organic materials is a key issue in molecular electronics. Field effect transistors
(FET) are not only a powerful tool to measure charge transport at the interface level but are
also an essential element in modern electronics. In this talk, a general overview in molecular
electronics will be given, with particular emphasis on materials, some device applications and
in more detail organic field effect transistors (OFET). Single crystal OFET measurements
performed on 3 different systems, TMTSF, PDIF-CN2 and TTF/TCNQ will be presented and
some of the key topics in OFETs will be discussed. TMTSF devices show clear signatures of
intrinsic transport (high mobility, increasing with lowering temperature) and p-type behaviour.
PDIF-CN2 presents n-type transport and very good device characteristics with roomtemperature
electron mobility as high as 6 cm2/Vs in vacuum and 3 cm2/Vs in air, the best ntype
mobility reported until the moment in an OFET. Finally, it will be introduced a new
electronic system created at the interface of two different organic crystals. Despite the fact that
the two organic crystals (TTF and TCNQ) are large gap semiconductors and, therefore
essentially insulating, their interface turns out to exhibit metallic character, with very high
conductivity becoming larger as the temperature is lowered. As the interface assembly process
is simple and can be applied to crystals of virtually any conjugated molecule, the combination
of molecules with different electronic properties will then enable the assembly of molecular
interfacial systems possessing properties that have no analogue in molecular bulk materials.

 

Date: 2008-Nov-26     Time: 12:00:00     Room: Auditório do INESC-Avila, Av. Duque de Ávila, 23

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