Deposition of Polymer-Free and Locally Aligned Semiconducting Carbon Nanotube Networks Via a Vapor-Mediated Marangoni Effect for High-Performance Field Effect Transistors

Semiconducting single-walled carbon nanotubes (s-SWNTs) have drawn significant attention in the last few decades, thanks to their exceptional electronic, optical, and mechanical properties. Although a variety of solution processing methods with polymer-wrapped s-SWNTs have promised to produce high-quality films, deposition of s-SWNTs with a precisely controlled nanostructure and film property remains formidable. Adding to this hurdle is the complete removal of the wrapping polymer during device fabrication as the insulating polymer strongly impedes charge injection and transport. In this work, we demonstrate a degradable polymer, poly[(9,9-dioctylfluorenyl-2,7-diyl))- alt -co-(4,4’-azobenzene)], to obtain polymer-free s-SWNTs, and a deposition scheme utilizing ethanol to induce the Marangoni effect to deposit locally aligned s-SWNT network films. Field-effect transistors (FETs) comprising these films as active layers exhibit an average on-state current of 2.5 μA/μm at the source-drain voltage of −1 V (V ds = −1 V), which is among the highest in s-SWNT FETs with s-SWNT network films. Our technique can yield s-SWNT network films with locally controlled morphology and a polymer-free s-SWNT surface across a wafer scale, making it amenable for broad applications in high-performance s-SWNT electronics.