Selective Dispersion of Large-Diameter Semiconducting Carbon Nanotubes by Functionalized Conjugated Dendritic Oligothiophenes for Use in Printed Thin Film Transistors

Selective dispersion of semiconducting single walled carbon nanotubes (s-SWCNTs) by conjugated polymer wrapping is recognized as the most promising scalable method for s-SWCNT separation. Despite a number of linear conjugated polymers being reported for use in s-SWCNT separation, these linear polymers suffer batch-to-batch variation for their undefined molecular structure. Here, it is reported that conjugated dendritic oligothiophenes with multiple diketopyrrolopyrrole groups at the periphery have the capability of selectively dispersing large diameter s-SWCNTs with high dispersion efficiency and certain chiral selectivity. Printed top-gated thin film transistors using the dendrimer sorted s-SWCNTs show high charge carrier mobility of up to 57 cm² V⁻¹ s⁻¹ and on/off ratios of ≈10⁶ with high reproducibility, which is ascribed to the defined and monodispersed molecular structure of dendrimers. Moreover, owing to the multiple peripheral anchoring groups of these dendritic molecules, these dendrimer-s-SWCNT dispersions display excellent stability. The current work proves that dendritic molecules are excellent dispersion reagents for s-SWCNT separation.