Conductivity of inkjet-printed PEDOT:PSS-SWCNTs on uncoated papers

Poly(3,4-ethylenedioxythiopene): poly (styrene-sulfonate), or PEDOT:PSS, as well as singlewalled carbon nanotubes, were incorporated into an inkjet ink. Handsheets were prepared which contained varying amounts of TiO2filler, internal sizing agent, fixation agent, and either softwood or hardwood kraft pulp. The ink was jetted onto the handsheets to form conductive layers with apparent conductivity as high as 0.018 S/cm on internally alkyketene dimer-sized softwood kraft handsheets with no other additives. Internal sizing increased conductivity at low filler loadings by preventing PEDOT:PSS from penetrating into the substrate, resulting in a conductive ink film on the surface of the sample. Unsized handsheets allowed more rapid absorption, and therefore deeper penetration, of the PEDOT:PSS ink, which resulted in a more diffuse conductive layer. The inclusion of a polyethyleneimine retention aid for TiO2filler decreased conductivity significantly even in unfilled sheets by interaction with PSS-counterions. A positively charged fixation agent, poly(diallyldimethylammonium) chloride, reduced PEDOT conductivity through the retention of nonconductive PSS-anions.