Width-Spreading Effect in Printed Carbon Nanotube Thin-Film Transistors and Its Impact on Device Performance

Printed carbon nanotube (CNT) thin-film transistors (TFTs) are promising candidates for next-generation electronics. Due to the necessary wrapping polymer used to disperse CNTs in solution, a postprinting method is needed to remove the polymer from the thin-film channel to realize the desired semiconducting properties. A commonly used method for this is solvent rinsing, which we report induces an overlooked and pronounced channel width-spreading effect. This effect leads to underestimation of the CNT channel width and reduces the accuracy of calculated performance metrics depending on the geometry. In this work specifically, aerosol jet-printed CNT-TFTs exhibit expansion from an intended width of 300 μm to ∼3.5 mm, reducing width-normalized on-current from 7 to 0.6 μA/mm for toluene-rinsed devices. Patterned O2 plasma etching is used to restore the intended channel dimensions of rinsed devices but also reduces their apparent Ion from 25 to 12 μA/mm, implying that unwanted CNTs account for at least 50% of Ion. Other parameters like mobility are also affected, dropping from 25.1 to 2.41 cm² V^–1 s^–1. A solution to this width-spreading effect is demonstrated, involving a combination of postprint baking and rinsing that preserves the intended, as-printed channel dimensions. These findings emphasize the critical need for width verification and careful postprint processing in benchmarking printed CNT-TFTs.

Duke Scholars

Author Aaron D. Franklin Pierre R. Lamond Department of Electrical and Computer Engin ...