Dispersion of High-Purity Semiconducting Arc-Discharged Carbon Nanotubes Using Backbone Engineered Diketopyrrolopyrrole (DPP)-Based Polymers

Abstract

The isolation of semiconducting single-walled carbon nanotubes (sc-SWNTs) with ideal diameter and high purity is highly desired for high-performance electronic devices. However, current sorting methods for large-diameter sc-SWNTs suffer from either low purity (<99%) or long processing time (>20 h). Here, a backbone-engineering strategy is reported for the polymer used for sorting to improve the purity of sorted sc-SWNTs. Six diketopyrrolopyrrole (DPP)-based conjugated polymers are used to systematically investigate their sorting ability for sc-SWNTs. It is found that incorporation of more thiophenes building blocks in the repeating units of DPP polymer backbone leads to increased selectivity and yield for sc-SWNTs. The DPP polymers can disperse sc-SWNTs with 1.4-1.6 nm in diameter and high purity of 99.6% by a processing time as short as 1 h. Furthermore, a scalable film coating method named "solution shearing" is used to fabricate SWNT network thin-film transistors (TFTs). The TFT devices exhibit both high mobilities over 50 cm(2) V-1 s(-1) and high on/off ratios over 10(5), which are among the highest performance for solution-processed SWNT network TFTs.