In this paper, we report a novel patterning method for a poly(3,4-ethylenedioxythiophene) (PEDOT) nanofilm deposited on an OTS monolayer-coated silicon wafer substrate by the vapor phase polymerization method. To scrutinize the adhesion improvement, electrical conductivity and feature controllability, patterned PEDOT nanofilms were investigated with a Scotch tape peel test, I-V curve measurement, and optical and atomic force microscopes. The scrutinization strongly indicates that the adhesion improvement is most likely due to direct chemical bonds formed between ethylenedioxythiophene (EDOT) molecules and photo-oxidized OTS monolayer during a vapor phase polymerization reaction. The investigation also discovered that the feature size of the film can be chemically controlled by the reaction between OTS and reactive atomic oxygen gases, and the patterned films generally show a noticeably good electrical conductivity (approximately 500 S/cm at merely approximately 100 nm thick film). These results successfully demonstrate that the patterned PEDOT nanofilms are qualified enough to be employed as an electrode component of an OTFT device since the electrode materials must show an electrical conductivity of at least 50 S/cm or higher.

We have investigated a novel method for patterning of (3, 4-ethylenedioxythiophene) PEDOT, which has involved a selective polymerization of PEDOT on an UV-activated Self-Assembled-Monolayer surface. OTS coated surface has been activated by UV exposure, and the UV-exposed area served as adsorption sites for FeCl3 oxidants, providing a selective deposition of PEDOT films on FeCl3 adsorbed area, and thus leading to the selective patterning of PEDOT films. UV irradiation time and mask pattern dimension are main contributors to patternability: UV irradiation through Cr-mask (3 microm design) lead to approximately 3-5 microm patterns of PEDOT films, depending on the UV exposure time. In addition, a scotch tape peel test revealed excellent adhesion property of PEDOT to SiO2. Consequently, this simple method can be applied to define deep submicron dimensions due to its ability of providing a direct transfer of mask patterns to the substrate.