Charge transport in semiconducting carbon nanotube networks

TL;DR

This review discusses models, experimental techniques, and recent advances in understanding charge transport in semiconducting carbon nanotube networks, highlighting their importance for electronic device applications.

Contribution

It provides a comprehensive overview of charge transport models, experimental characterization methods, and recent progress enabled by improved nanotube synthesis and sorting.

Findings

Advances in nanotube purification improve device performance.

Various spectroscopic and microscopy techniques reveal charge distribution.

Understanding microscopic parameters guides optimization of nanotube networks.

Abstract

Efficient and controlled charge transport in networks of semiconducting single-walled carbon nanotubes is the basis for their application in electronic devices, especially in field-effect transistors and thermoelectrics. The recent advances in selective growth, purification, and sorting of semiconducting and even monochiral carbon nanotubes have enabled field-effect transistors with high carrier mobilities and on/off current ratios that were impossible a few years ago. They have also allowed researchers to examine the microscopic interplay of parameters such as nanotube length, density, diameter distribution, carrier density, intentional and unintentional defects, dielectric environment, etc., and their impact on the macroscopic charge transport properties in a rational and reproducible manner. This review discusses various models that are considered for charge transport in nanotube networks and the experimental methods to characterize and investigate transport beyond simple conductivity or transistor measurements. Static and dynamic absorption, photoluminescence and electroluminescence spectroscopy, as well as scanning probe techniques (e.g., conductive atomic force microscopy, Kelvin probe force microscopy), and their unique insights in the distribution of charge carriers in a given nanotube network and the resulting current pathways will be introduced. Finally, recommendations for further optimization of nanotube network devices and a list of remaining challenges are provided.