# High-Performance Semiconducting Carbon Nanotube Transistors Using Naphthalene Diimide-Based Polymers with Biaxially Extended Conjugated Side Chains

## TL;DR

This paper shows that modifying polymer side chains improves the performance of carbon nanotube transistors by enhancing sorting and wrapping efficiency.

## Contribution

The study introduces biaxially extended conjugated side chains in naphthalene diimide-based polymers to improve semiconducting carbon nanotube sorting and device performance.

## Key findings

- P3 polymer with branched side chains forms larger bundles of high-purity semiconducting SWNTs.
- P3/sc-SWNT transistors achieve a hole mobility of 4.72 cm² V⁻¹ s⁻¹ and high stability.
- π–π stacking interactions between CPs and SWNTs are confirmed via X-ray diffraction.

## Abstract

Polymer-wrapped single-walled
carbon nanotubes (SWNTs) are a potential
method for obtaining high-purity semiconducting (sc) SWNT solutions. Conjugated polymers (CPs) can selectively sort sc-SWNTs with different chiralities, and the structure of
the polymer side chains influences this sorting capability. While
extensive research has been conducted on modifying the physical, optical,
and electrical properties of CPs through side-chain modifications,
the impact of these modifications on the sorting efficiency of sc-SWNTs remains underexplored. This study investigates
the introduction of various conjugated side chains into naphthalene
diimide-based CPs to create a biaxially extended conjugation pattern.
The CP with a branched conjugated side chain (P3) exhibits
reduced aggregation, resulting in improved wrapping ability and the
formation of larger bundles of high-purity sc-SWNTs.
Grazing incidence X-ray diffraction analysis confirms that the potential
interaction between sc-SWNTs and CPs occurs through
π–π stacking. The field-effect transistor device
fabricated with P3/sc-SWNTs demonstrates
exceptional performance, with a significantly enhanced hole mobility
of 4.72 cm2 V–1 s–1 and high endurance/bias stability. These findings suggest that biaxially
extended side-chain modification is a promising strategy for improving
the sorting efficiency and performance of sc-SWNTs
by using CPs. This achievement can facilitate the development of more
efficient and stable electronic devices.