Patterning polythiophene films using electrochemical over-oxidation

Abstract

Over-oxidative degradation of polythiophenes, which breaks the conjugation and destroys the electronic conductivity of the polymer, is well documented as a liability in these materials. We use this 'weakness', via controlled electrochemical over-oxidation, in a novel subtractive patterning technique compatible with high-speed reel-to-reel printing technology. We demonstrate the use of electrochemical over-oxidation to pattern PEDOT:PSS films via an x-y plotter, silk-screen and high-resolution photolithographic techniques, resulting in patterning down to a resolution of 2 µm and a conduction contrast between unpatterned and patterned areas of up to 10 8 .

Logic gates based on ion transistors

“…Through sequential photolithographic and etching steps, the structures are patterned and chemically modified to achieve the final device. The cationselective layer is obtained by overoxidizing 24 PEDOT:PSS, which terminates the electronic conductivity of the PEDOT phase while leaving the PSS phase intact. The anion selective layer consist of quaternized and crosslinked poly(vinylbenzylchloride) (PVBC) and the insulating layers are made from photopolymerized SU8.…”

Patterning and Conductivity Modulation of Conductive Polymers by UV Light Exposure

“…Tehrani et al used electrochemical overoxidation as a patterning technique for PEDOT and they were able to achieve a 7 orders of magnitude difference in conductivity between exposed and non-exposed regions. [14] In this work we report a new method of patterning vapor phase polymerized PEDOT:Tos using UV light. Similar to the work by Kim [13] and Tehrani et al [14] , it involves a spatially controlled reduction in conductivity.…”

“…[14] In this work we report a new method of patterning vapor phase polymerized PEDOT:Tos using UV light. Similar to the work by Kim [13] and Tehrani et al [14] , it involves a spatially controlled reduction in conductivity. However, the technique reported herein differs from previous studies in the exposure of the oxidant prior to polymerization resulting in a reduction in the polymer conductivity.…”

Toward Complementary Ionic Circuits: The npn Ion Bipolar Junction Transistor

“…A thin film of the conductive polymer [15][16] poly(3,4-ethylenedioxythiophene) 17 doped with the polyanion poly(styrenesulfonate) (PEDOT:PSS) coated on a plastic (PET) foil is used as substrate. The cation-selective base comprises overoxidized 18 PEDOT:PSS, i.e. leaving PSS ionically conductive and PEDOT electronically non-conducting.…”