High-resolution and scalable printing of highly conductive PEDOT:PSS for printable electronics

Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a primary candidate for the conductive material in printable electronics. Currently, lateral resolutions down to only 30 μm have been demonstrated for roll-to-roll (R2R)-compatible PEDOT:PSS printing. However, increasing lateral resolution of the printing technique can increase the complexity/ability of printed devices. Topographical discontinuous dewetting (TDD) and liquid-bridge transfer (LBT) is employed as a high-resolution, scalable, R2R-compatible patterning technique to fabricate PEDOT:PSS patterns with down to 400 nm lateral resolution and high thicknesses. PEDOT:PSS ink dispersions were prepared with water/ethanol/cosolvent mixtures to enable the TDD process and ensure high conductivity. After transfer by LBT to target substrates, an impressive average conductivity of 20.5 S cm⁻¹ was measured for the transferred PEDOT:PSS patterns without any post-transfer conductivity-enhancing treatments. Post-transfer conductivity-enhancing treatments were applied that are device fabrication-compatible (acid-free) with very high conductivities up to ∼2590 S cm⁻¹ and average conductivity of ∼1190 S cm⁻¹ for PEDOT:PSS lines patterns fabricated with 4.3% dimethylformamide (DMF) cosolvent. Interestingly, DMF cosolvent in the PEDOT:PSS ink dispersion formed higher conductivity line patterns due to different drying dynamics. This work demonstrates a path to achieve high-resolution, scalable, R2R-compatible printing of PEDOT:PSS patterns while maintaining very high conductivities for future advanced printable electronic devices.