Nanoscale Charge Percolation Analysis in Polymer‐Sorted (7, 5) Single‐Walled Carbon Nanotube Networks. Issue 31 (4th July 2016)

• Record Type: Journal Article
• Authors: Bottacchi, Francesca; Bottacchi, Stefano; Späth, Florian; Namal, Imge; Hertel, Tobias; Anthopoulos, Thomas D.
• Is Part Of: Small. Volume 12:Issue 31(2016)
• Page Start: 4211
• Page End: 4221
• Publication Date: 2016-07-04
• Subjects: carbon nanotubes -- conductive atomic force microscopy -- network percolation -- surface characterization -- transistors; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201600922
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract : The current percolation in polymer‐sorted semiconducting (7, 5) single‐walled carbon nanotube (SWNT) networks, processed from solution, is investigated using a combination of electrical field‐effect measurements, atomic force microscopy (AFM), and conductive AFM (C‐AFM) techniques. From AFM measurements, the nanotube length in the as‐processed (7, 5) SWNTs network is found to range from ≈100 to ≈1500 nm, with a SWNT surface density well above the percolation threshold and a maximum surface coverage ≈58%. Analysis of the field‐effect charge transport measurements in the SWNT network using a 2D homogeneous random‐network stick‐percolation model yields an exponent coefficient for the transistors OFF currents of 16.3. This value is indicative of an almost ideal random network containing only a small concentration of metallic SWNTs. Complementary C‐AFM measurements on the other hand enable visualization of current percolation pathways in the xy plane and reveal the isotropic nature of the as‐spun (7, 5) SWNT networks. This work demonstrates the tremendous potential of combining advanced scanning probe techniques with field‐effect charge transport measurements for quantification of key network parameters including current percolation, metallic nanotubes content, surface coverage, and degree of SWNT alignment. Most importantly, the proposed approach is general and applicable to other nanoscale networks, including metallic nanowires as well as hybrid nanocomposites. Abstract : A novel approach for studying the current percolation behavior in solution‐deposited semiconducting two‐dimensional networks composed of single‐walled carbon nanotubes (SWNTs) is reported. The method which relies on the combination of atomic force microscopy and electrical field‐effect measurements allows for the analysis of important network properties including surface coverage, metallic SWNTs content, degree of alignment and charge percolation with nanometer lateral resolution.