N-Type Conjugated Polymer-Enabled Selective Dispersion of Semiconducting Carbon Nanotubes for Flexible CMOS-Like Circuits

Abstract

Sorting of semiconducting single-walled carbon nanotubes (SWNTs) by conjugated polymers has attracted considerable attention recently because of its simplicity, high selectivity, and high yield. However, up to now, all the conjugated polymers used for SWNT sorting are electron-donating (p-type). Here, a high-mobility electron-accepting (n-type) polymer poly([N,N-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5-(2,2-bithiophene)) (P(NDI2OD-T2)) is utilized for the sorting of high-purity semiconducting SWNTs, as characterized by Raman spectroscopy, dielectric force spectroscopy and transistor measurements. In addition, the SWNTs sorted by P(NDI2OD-T2) have larger diameters than poly(3-dodecylthiophene) (P3DDT)-sorted SWNTs. Molecular dynamics simulations in explicit toluene demonstrate distinct linear or helical wrapping geometry between P(NDI2OD-T2) and different types of SWNTs, likely as a result of the strong interactions between the large aromatic core of the P(NDI2OD-T2) backbone and the hexagon path of SWNTs. By using high-mobility n-type P(NDI2OD-T2) as the sorting polymer, ambipolar SWNT transistors with better electron transport than that attained by P3DDT-sorted SWNTs are achieved. As a result, flexible negated AND and negated OR logic circuits from the same set of ambipolar transistors are fabricated, without the need for doping. The use of n-type polymers for sorting semiconducting SWNTs and achieving ambipolar SWNT transistor characteristics greatly simplifies the fabrication of flexible complementary metal-oxide-semiconductor-like SWNT logic circuits.