Exploring Silver Contact Morphologies in Printed Carbon Nanotube Thin-Film Transistors

Abstract

Demand for ubiquitous and flexible electronics to facilitate the rapid growth of Internet- of- Things (IoT) technologies has driven the advancement of printed electronics for low-cost and high-throughput manufacturing. The carbon nanotube thin-film transistor (CNT-TFT) is one of the most promising options for printed electronics due to its mechanical flexibility, compatibility with low-temperature fabrication, and relatively high mobility [1]. Meanwhile, Ag nanoparticles remain the most widely used conductive material in printed inks due to their superb dispersion stability, high conductivity, and relatively low cost [2]. However, limited studies have explored the impact of different printed metallic contacts in CNT-TFTs [3], even though the contact interfaces are one of the leading factors limiting performance. In this work, the impact of Ag contact morphology is studied for the first time by fabricating hundreds of CNT-TFTs using an aerosol jet printer to systematically investigate three morphologies (nanoparticle (NP), nanoflake (NF), and nanowire (NW), as seen in Fig. 1) and their impact on device performance. Using what is learned from the contact morphology results, the first CNT-TFTs printed without removal of the substrate from the printer (full “print-in-place” additive devices) are also demonstrated.