Conference Program - LOPE-C 2011

SCIENTIFIC CONF. | THURSDAY-JUNE 30, 2011
Track 4
Novel Inks and Processes (04:30 pm - 06:00 pm) | LOCATION HARMONIE D / LEVEL C2
04:30 pm Design of semiconducting materials and polymer dielectrics for printed transistor applications
Dr Silvia Janietz,
FhG-IAP, Germany
OFETs based on solution-processible polymers as well as small organic molecules have obtained impressive improvements in performance in the last years. But the aim is
to realize integrated circuits based only on organic components to reach the potential for low cost processing. A critical point in the OFET is the complete system organic
semiconductor/ organic dielectric. On the one side the interface between the organic dielectric and the organic semiconductor could be influenced through modification of
the chemical structure of the applied semiconductor polymer. Therefore a novel poly(3-[hexyl-co-3,6-dioxaheptyl]-thiophene) was synthesized. The dioxaheptyl-groups in
the side chain of the polymer backbone result in good wetting behavior of the PMMA-solution on top of the P3HT-doh layer which we do not observe when we use
P3HT-layers. The measured performance on flexible OFETs regarding mobility seems comparable as well. The copolymer was formulated for inkjet printing processes and
we determine a comparable behavior characteristic of the OTFT to devices that based on spin-coated semiconductor layers. On the other side new adapted organic
dielectrics are developed to adjust the interface to the organic semiconductor. For this reason new thermally crosslinkable dielectrics are synthesized which have the
opportunity to integrate different kind of monomer units to adapt the organic semiconductor. At first inert polymers were prepared with two different crosslinkable units.
These polymers have the possibility to be crosslinkable in a thin layer through a following thermal or UV-initiated step. The polymers were synthesized through a radical
solution polymerisation. The copolymers consist of phenol- and phenoxymethyloxiran-units in different ratios in the polymer backbone. This synthetic strategy offers the
possibility to realize very thin dielectric layers to reduce the operation voltage of OFETs to some volts. The electrical stability of thin layers using this dielectric as well as the
functionality in OFETs were proven.
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