Inkjet printing of transparent and conductive patterns of single-walled carbon nanotubes and PEDOT-PSS composites

Transparent and conductive patterns of carboxyl functionalized single‐walled carbon nanotubes (SWCNT‐COOHs) and the composites of those with poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT‐PSS) were deposited on various substrates by inkjet printing.
For low print repetitions, the PEDOT‐PSS/SWCNT‐COOH composite patterns show enhanced conductance as compared to the corresponding PEDOT‐PSS conductors. The results suggest a decreased percolation threshold for the printed composite since the nanotubes establish electrical interconnections between the separate PEDOT‐PSS (conductive phase) islands being dispersed in the insulating PSS‐phase.
However, the interaction between PEDOT‐PSS and SWCNTs becomes insignificant and the conductivity is not enhanced by the nanotubes, when the amount of PEDOT‐PSS is sufficient to form a continuous conducting phase. Up to now, patterns having sheet resistivities as low as ∼1 kΩ/□ could be achieved.
Though there is a trade‐off between transparency and conductivity – we achieved highly transparent patterns (∼90%) with a reasonably low resistivity of ∼10 kΩ/□.
The ink and printing method proposed here offer new alternatives of conventional transparent conductive materials based on either polymers or indium oxides; and pose scaleable production of cost‐effective transparent electronics.