Micropatterning of Electrodes by Microcontact Printing Method and Application to Thin Film Transistor Devices

Electrode micropatterning without etching was successfully achieved by the microcontact printing (µCP) method. We used a conductive polymer poly(3,4-ethylenedioxythiophene)/poly(4-stylenesulfonate) (PEDOT/PSS) as an electrode material. We controlled the surface free energy of poly(dimethylsiloxane) (PDMS) by exposure to vacuum ultraviolet (VUV) light with a wavelength of 172 nm using an excimer lamp. Consequently, we established an inking technique for PEDOT/PSS aqueous dispersion on a PDMS elastomer stamp. The micropatterns of PEDOT/PSS thin films of 1 µm width were fabricated by transferring the PEDOT/PSS aqueous dispersion on the PDMS elastomer stamp to another substrate by the µCP method. Furthermore, we fabricated top contact (TC) organic thin film transistors (OTFTs) with PEDOT/PSS as source and drain electrodes. We demonstrated the successful operation of the fabricated OTFTs with a channel length of 5 µm and an electrode width of 8 µm. Results show that the µCP method is promising for application to various devices that require micropatterning.