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ACS Nano. 2018 Jun 26;12(6):5482-5488. doi: 10.1021/acsnano.8b00909. Epub 2018 May 14.

Patterned Liquid Metal Contacts for Printed Carbon Nanotube Transistors.

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Department of Electrical and Computer Engineering , Duke University , Durham , North Carolina 27708 , United States.
Department of Chemical and Biomolecular Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States.
Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States.


Flexible and stretchable electronics are poised to enable many applications that cannot be realized with traditional, rigid devices. One of the most promising options for low-cost stretchable transistors are printed carbon nanotubes (CNTs). However, a major limiting factor in stretchable CNT devices is the lack of a stable and versatile contact material that forms both the interconnects and contact electrodes. In this work, we introduce the use of eutectic gallium-indium (EGaIn) liquid metal for electrical contacts to printed CNT channels. We analyze thin-film transistors (TFTs) fabricated using two different liquid metal deposition techniques-vacuum-filling polydimethylsiloxane (PDMS) microchannel structures and direct-writing liquid metals on the CNTs. The highest performing CNT-TFT was realized using vacuum-filled microchannel deposition with an in situ annealing temperature of 150 °C. This device exhibited an on/off ratio of more than 104 and on-currents as high as 150 μA/mm-metrics that are on par with other printed CNT-TFTs. Additionally, we observed that at room temperature the contact resistances of the vacuum-filled microchannel structures were 50% lower than those of the direct-write structures, likely due to the poor adhesion between the materials observed during the direct-writing process. The insights gained in this study show that stretchable electronics can be realized using low-cost and solely solution processing techniques. Furthermore, we demonstrate methods that can be used to electrically characterize semiconducting materials as transistors without requiring elevated temperatures or cleanroom processes.


carbon nanotube; direct-writing; eutectic gallium−indium; liquid metal; nanomaterials; stretchable electronics; thin-film transistor


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