Single-walled carbon nanotubes have the electrical and mechanical properties that may enable next-generation wearable sensors and flexible electronics. However, nanotubes are cut to short pieces (typically less than 1 μm) by sonication during solution processing, which downgrades their otherwise extraordinary properties. Another challenge is that these atomically-thin materials are prone to chemical attack because all of the constituent atoms are exposed. In this talk, I will discuss recent progress from our lab in addressing these challenges and some new opportunities that arise. Particularly, we have introduced a technique called “superacid-surfactant exchange (S2E)” which allows for non-destructive dispersion and scalable sorting of ultralong nanotubes in aqueous solutions. We will show that long, metallic double-walled carbon nanotubes can simultaneously attain ultrahigh electrical conductivity, mechanical stretchability, and optical transparency, all three key properties that are required to achieve high performance stretchable transparent conductive films. Particularly, thin films fabricated from 3.2 μm long nanotubes show a record high electrical conductivity of 3316 S/cm at 100% tensile strain and 85% optical transmittance. After 1000 repetitions of release-stretch cycles (between 0 and 100% strain), the decay in thin-film conductivity is a mere 4%, significantly better than the short nanotube controls (0.8 um on average), which decayed by 95%. We further show that this dramatic improvement arises from the long length (3.2 μm versus 0.8 μm on average) and metallic nature of the purified nanotubes. As an illustration of potential applications, we fabricated a wearable device, which exhibited steady and high current output under significantly large shape changes. We further show that thin film transistors fabricated from ultralong semiconducting nanotubes can attain a carrier mobility exceeding 90 cm2 V-1 s-1. Time permitting, I will also discuss our progress in the synthesis of a tube-in-a-tube semiconductor (Tube^2) that uniquely combines both protected electronic properties and surface functionalities for electrical detection of small molecules.

Materials challenges and opportunities for carbon nanotubes-based flexible electronics and wearable sensors

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.