Relationship between Density Changes and Electrical Properties of Chemically Self-Assembled Monolayer Single-Walled Carbon Nanotube Networks by Controlling Anchoring Density

Abstract

Single-walled carbon nanotubes (SWNTs) are valued for their high carrier mobility, tunable band gaps, and strong mechanical properties, making them promising for electronic applications. However, the presence of metallic SWNTs in mixtures impairs device performance, requiring the isolation of semiconducting SWNTs (sc-SWNTs). Conjugated polymer wrapping is a leading technique for this selective separation owing to its simplicity and high selectivity; however, challenges persist in achieving optimal SWNT density, uniformity, and reproducibility. In this study, chemically self-assembled monolayer sc-SWNTs are fabricated using a click reaction on prepatterned alkyne-functional adhesion layers. We elucidated the effect of variations in the azide content on the sc-SWNT selectivity, SWNT number density, uniformity, and network distribution, as well as its subsequent effect on the field-effect transistor (FET) performance. In addition, we propose gradually reducing azide functionalization in wrapping polymer side chains to enhance the sc-SWNT selectivity while maintaining effective chemical self-assembly. The sc-SWNT purity, film density, and FET performance were significantly improved when the azide content was reduced to a certain level. This study offers a pathway to enhance sc-SWNT selectivity, purity, and device performance via azide functionalization optimization, advancing the commercialization of SWNT-based electronics.