Flexible, Print-in-Place 1D-2D Thin-Film Transistors Using Aerosol Jet Printing

Semiconducting carbon nanotubes (CNTs) printed into thin films offer high electrical performance, significant mechanical stability, and compatibility with low-temperature processing. Yet, the implementation of low-temperature printed devices, such as CNT thin-film transistors (CNT-TFTs), has been hindered by relatively high process temperature requirements imposed by other device layers—dielectrics and contacts. In this work, we overcome temperature constraints and demonstrate 1D-2D thin-film transistors (1D-2D TFTs) in a low-temperature (maximum exposure ≤ 80 °C) full print-in-place process (i.e., no substrate removal from printer throughout the entire process) using an aerosol jet printer. Semiconducting 1D CNT channels are used with a 2D hexagonal boron nitride (h-BN) gate dielectric and traces of silver nanowires as the conductive electrodes; all deposited using the same printer. The aerosol jet-printed 2D h-BN films were realized via proper ink formulation, such as utilizing the binder hydroxypropyl methylcellulose, which suppresses re-dispersion between adjacent printed layers. In addition to an ON/OFF current ratio up to 3.5×〖10〗^5, channel mobility up to 10.7 cm^2·V^(-1)·s^(-1), and low gate hysteresis, 1D-2D TFTs exhibit extraordinary mechanical stability under bending due to the nanoscale network structure of each layer, with minimal changes in performance after 1000 bending test cycles at 2.1 % strain. It is also confirmed that none of the device layers requires any high-temperature treatments to realize optimal performance. These findings provide an attractive approach towards a cost-effective, direct-write realization of electronics.