Ion-and Charge Transport in Dense Films of Semiconducting Single-Walled Carbon Nanotubes

Dispersions of purely semiconducting single-walled carbon nanotubes (SWCNTs) can be sorted and purified by polymer-wrapping and subsequently printed into thin or thick SWCNT films that are suitable for various electronic devices. Here, we demonstrate that these porous composites of conjugated polymer and semiconducting nanotubes enable mixed ionic and electronic transport with high charge carrier mobilities in electrochemical transistors with different electrolytes. The ionic transport and hence also the effective volumetric capacitance of the nanotube network can be increased substantially by changing from a hydrophobic polyfluorene copolymer with alkyl sidechains to one with tetraethylene glycol sidechains, thus reaching over 200 Fcm⁻¹V⁻¹s⁻¹ as the product of carrier mobility and volumetric capacitance (<i>ACS Appl. Mater. Interfaces </i>2022, <i>14</i>, 8209). We find that the maximum transconductance for hole transport in SWCNT networks also depends on the size of the electrolyte anions, suggesting a direct impact on the delocalization of charge carriers along the nanotubes. Furthermore, we monitor the ion movement and thus charge carrier concentration within a nanotube network by spatially resolved in-situ Raman- and photoluminescence spectroscopy and explore the role of the network morphology and density for both charge and ion transport. Finally, we demonstrate the direct sensing of cupric ions and indirectly of glyphosate in water-gated transistors with polyfluorene copolymer-wrapped nanotubes (<i>Nanoscale </i>2022, <i>14</i>, 13542).