Web Release Date: November 20,
Solution-Processed Organic Field-Effect Transistors and Unipolar Inverters Using Self-Assembled Interface Dipoles on Gate Dielectrics
and
Department of Materials Science and Engineering and Department of Electrical and Computer Engineering, G. W. C. Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland 21218
Received August 6, 2007
In Final Form: October 2, 2007
Abstract:
Self-assembled monolayers (SAMs) of polarized and nonpolarized organosilane molecules on gate insulators induced tunable threshold voltage shifting and current modulation in organic field-effect transistors (OFETs) made from solution-deposited 5,5'-bis(4-hexylphenyl)-2,2'-bithiophene (6PTTP6), defining depletion-mode and enhancement-mode operation. p-Channel inverters were made from pairs of OFETs with an enhancement-mode driver and a depletion-mode load to implement full-swing and high-gain organic logic circuits. The experimental results indicate that the shift of the transfer characteristics is governed by the built-in electric field of the SAM. The effect of surface functional groups affixed to the dielectric substrate on the grain appearance and film mobility is also determined.
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