Polymer Gate Dielectric Surface Viscoelasticity Modulates Pentacene Transistor Performance
Choongik Kim,
Antonio Facchetti,*
Tobin J. Marks*
Nanoscopically confined polymer films are known to exhibit substantially
depressed glass transition temperatures (
Lg's) as compared to
the corresponding bulk materials. We report here that pentacene
thin films grown on polymer gate dielectrics at temperatures
well below their bulk
Tg's exhibit distinctive and abrupt morphological
and microstructural transitions and thin-film transistor (TFT)
performance discontinuities at well-defined growth temperatures.
The changes reflect the higher chain mobility of the dielectric
in its rubbery state and are independent of dielectric film
thickness. Optimization of organic TFT performance must recognize
this fundamental buried interface viscoelasticity effect, which
is detectable in the current-voltage response.
* To whom correspondence should be addressed. E-mail: a-facchetti{at}northwestern.edu (A.F.); t-marks{at}northwestern.edu (T.J.M.)
