In this paper, we report a method for the inkjet printing of single-walled carbon nanotube thin-film transistors (SWCNT TFTs). Although inkjet technology is a powerful tool for the fabrication of SWCNT TFTs, the diameter of the ink droplets (100 μm) strictly limits the device size. Here, we surmount this limitation by combining inkjet technology and site-selective deposition based on the patterning of self-assembled monolayers. We have synthesized patterned SWCNT films with feature widths less than 100 μm using this site-selective surface modification method, thus improving the performance limit of SWCNT printed electronics.

We report a method for the inkjet printing of aligned single-walled carbon-nanotube (SWCNT) films by combining inkjet technology with the strong wettability contrast between hydrophobic and hydrophilic areas based on the patterning of self-assembled monolayers. Both the drying process control using the strong wettability boundary and the coffee-stain effect strongly promote the aggregation of SWCNTs along the contact line of a SWCNT ink droplet, thereby demonstrating our achievement of inkjet-printed aligned SWCNT films. This method could open routes for developing high-performance and environmentally friendly SWCNT printed electronics.

The fabrication technology for emerging printed and flexible electronics is currently suboptimal. Although inkjet technology is a powerful tool for producing single-walled carbon nanotube (SWCNT) film transistors, inkjet printing at moderate temperatures (<100 °C) of complementary logic gates that are suitable for plastic substrates has yet to be realized. In this study, we describe how we surmounted these difficulties by combining SWCNTs and room-temperature-processable polymer dopant. We have successfully inkjet-printed SWCNT complementary inverters at 90 °C, thereby improving the performance limit of SWCNT electronics.

The fabrication of logic circuits using the inkjet technique has attracted especially strong interest owing to wide range applications such as flexible and printed electronics. Although logic circuits fabricated using the inkjet method have already been accomplished, the precise control of gate threshold voltages has not been realized yet. In this study, we have demonstrated electron doping of single-walled carbon nanotube (SWCNT) films by inkjet printing of dilute poly(ethylene imine) (PEI) ink. We have successfully obtained the continuous threshold voltage shift by varying the number of doping steps, indicating that the carrier concentration in PEI ink is much lower than that of our previous work.

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