Simple micro-patterning of high conductive polymer with UV-nano-imprinted patterned substrate and ethylene glycol-based second doping

We have developed a simple micro-patterning process for high conductive polymer (i.e., poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)) with a patterned substrate by using an ultraviolet (UV) nano-imprint and an ethylene glycol-based second doping technique. In the patterning process, the PEDOT:PSS water dispersion is first coated only on the hydrophilic area, which is fabricated by UV nano-imprinting, forming patterned PEDOT:PSS on the substrate. The patterned PEDOT:PSS film is then immersed in the ethylene glycol as a second doping technique for increasing its conductivity. The proposed process provides simplicity in terms of shorter process steps of the UV nano-imprinting and PEDOT:PSS coating and higher conductivity of patterned PEDOT:PSS film than existing complicated micro-fabrication processes for organic materials. The 200 nm wide nano-imprinted pillar structures change the wettability of the substrate where the contact angle of the substrate is decreased from 66.8° to 33.3°. The patterning resolution with the nano-imprinted pattern substrate is down to 100 m, which is useful for sensor applications. The conductivity increase delivers a low sheet resistance (120 Ω sq^-1) of patterned PEDOT:PSS film. Then, the patterning of PEDOT:PSS sensor shapes with its 300 m wide feature line and high conductivity are demonstrated. Therefore, our process leads to applications to a variety of PEDOT:PSS-based sensors.