Authors: S. Guha, G. Knotts, N.B. Ukah
Affilation: University of Missouri, United States
Pages: 45 - 48
Keywords: organic semiconductors, field-effect transistors, low k dielectrics, solution processable
We demonstrate low-operating voltage, high mobility, and stable organic field-effect transistors (OFETs) using both non-polar and polar polymeric dielectrics such as poly(4-vinyl phenol) (PVP), poly methyl metacrylate (PMMA), and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFe), dissolved in solvents of high dipole moment. High dipole moment solvents such as propylene carbonate (PC) and dimethyl sulfoxide (DMSO) used for dissolving the polymer dielectric, enhances charge carrier mobilities by orders of magnitude in pentacene OFETs compared to low dipole moment solvents. Fast switching circuits with patterned gate PVP-based pentacene OFETs demonstrated a switching frequency of 75 kHz at input voltages of |5V|. The frequency response of the OFETs is attributed to a high degree of dipolar-order in dielectric films obtained from high-polarity solvents and the resulting energetically ordered landscape for transport. Remarkably, these pentacene-based OFETs exhibited high stability under bias stress and in air with negligible shifts in the threshold voltage. Our results pave the way for high performance, stable, easily fabricated OFETs on flexible substrates, thus opening up a range of applications in real time fast organic logic circuits for radio frequency identity tags and e-paper applications.