RECEIVED DATE (automatically inserted by publisher); hdai@stanford.eduSingle-walled carbon nanotubes (SWNTs) exhibit advanced properties desirable for high performance nanoelectronics. Important to future manufacturing of high-current, speed and density nanotube circuits is large-scale assembly of SWNTs into densely aligned forms.1 Despite progress in oriented synthesis and assembly including the Langmuir-Blodgett (LB) method, 2-9 no method exists for producing assemblies of pristine SWNTs (free of extensive covalent modifications) with both high density and high degree of alignment of SWNTs. Here, we develop a LB method achieving monolayers of aligned non-covalently functionalized SWNTs from organic solvent with dense packing. The monolayer SWNTs are readily patterned for device integration by microfabrication, enabling the high currents (~3mA) SWNT devices with narrow channel widths. Our method is generic for different bulk materials with various diameters.Suspensions of as-grown laser-ablation and Hipco SWNTs in 1,2-dichloroethane (DCE) solutions of poly(m-phenylenevinylene -co-2,5-dioctoxy-p-phenylenevinylene) (PmPV) were prepared by sonication, ultra centrifugation and filtration (see supplementary information). The suspension contained mostly individual nanotubes (average diameter~1.3nm and ~1.8nm respectively for Hipco and laser-ablation materials, mean length ~500nm, Fig.1d and 1e) well solubilized in DCE without free unbound PmPV. PmPV is known to exhibit high binding affinity to SWNT sidewall via  stacking of its conjugated backbone ( Fig.1a) and thus impart solubility of nanotubes in organic solvents. 10 Indeed, we obtained homogeneous suspensions of nanotubes in PmPV solutions. However, we found that DCE was the only solvent in which PmPV bound SWNTs remained stably suspended when free unbound PmPV molecules were removed (Inset of Fig.1b). The PmPV treated SWNTs exhibited no aggregation in DCE over several months. DCE without PmPV could suspend low concentrations of SWNTs (~50X lower than with PmPV functionalization), insufficient for LB formation, especially for larger SWNTs in laser materials with lower solubility.The excitation and emission spectra of PmPV bound SWNTs (in PmPV-SWNT solution with excess PmPV removed) exhibited ~20nm and ~3nm shifts respectively relative to those of pure PmPV in DCE ( Fig.1b), providing spectroscopic evidence of strong interaction between PmPV and SWNTs. No change in the spectra was observed with the highly stable PmPV-SWNT/DCE suspension for months, indicating strong binding of PmPV on SWNT without detachment in DCE. The fact that PmPV-SWNTs were not stably suspended in other solvents without excess PmPV and that addition of large amounts of these solvents (e.g., chloroform) into a PmPV-SWNT/DCE suspension causing nanotube precipitation suggested significant detachment of PmPV from nanotubes in most organic solvents. The unique stability of PmPV coating on SWNT in DCE over other solvents is not fully understood currently. Nevertheless, it is highly desirable for ch...

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