Organic thin-film transistors fabricated by microcontact printing

We have fabricated organic thin-film transistors (OTFTs) using a microcontact printing technique (μCP) that employs thin polydimethylsiloxane stamps on a rigid silicon substrate in order to reduce macroscopic distortions. Systematic variation of the printing pressure, printing time, and concentration of eicosanethiol, the “molecular ink” in the μCP process, permits the fabrication of devices with smaller channel lengths (Leff) than nominally defined by the stamp. Interdigitated Ti/Au electrode structures with Leff down to 100 nm could be fabricated which, after additional surface treatment and vacuum deposition of αα′-dihexylquaterthiophene, yield OTFTs with excellent characteristics.