Regioregular poly(3-hexyl-thiophene) helical self-organization on carbon nanotubes

Abstract

Mixtures of regioregular poly(3-hexyl-thiophene) (rrP3HT) and multiwall carbon nanotubes have been investigated by scanning tunneling microscopy in ultrahigh vacuum. Carbon nanotubes covered by rrP3HT have been imaged and analyzed, providing a clear evidence that this polymer self-assembles on the nanotube surface following geometrical constraints and adapting its equilibrium chain-to-chain distance. Largely spaced covered nanotubes have been analyzed to investigate the role played by nanotube chirality in the polymer wrapping, evidencing strong rrP3HT interactions along well defined directions. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3173825

Hybrid Carbon Nanotube Networks as Efficient Hole Extraction Layers for Organic Photovoltaics

“…In terms of the geometry of rr-P3HT in the presence of SWNTs, previous reports on nanohybrids prepared using techniques similar to that described in this work have indicated experimentally (through scanning probe microscopic techniques) as well as computationally, a natural tendency for the rr-P3HT to wrap around SWNTs due to π-π type super-molecular interactions. 10,[21][22][23][24] To ascertain this fact further and to obtain a better understanding of the non-covalent functionalization process, optical absorption, valence and core level X-ray spectroscopy (XPS) measurements were carried out on the rr-P3HT/s-SWNT nanohybrid system. A representative UV-Vis absorbance spectrum for rr-P3HT/s-SWNT nanohybrids in 1,2-dichlorobenzene is shown in Fig.…”

Selective dispersion of high purity semiconducting single-walled carbon nanotubes with regioregular poly(3-alkylthiophene)s

“…Our geometrical model is different from the one introduced by Coleman and Ferreira 52 , which identifies energetically favourable coiling angles based on geometric constraints. In our case, we made assumptions on the possible polymer wrapping structures, either single and double strand with side chains interdigitated, based on the previous ultra-high-vacuum scanning tunnelling microscopy results by Giulianini et al 33 . The side-chain interdigitation is also supported by our own observation that the maximum dispersion concentration took place at around the same temperature for side-chain melting, indicating that the side-chain interaction places an important role in the polymer interaction with the SWNTs.…”

“…The geometrical model was devised based on the following: First, based on previous experimental observations, we assume that the polymer is able to wrap around a single SWNT 33,53 . Giulianini et al 33 reported a detailed experimental evidence of the regioregular poly(3-hexylthiophene) helical wrapping on CNTs by atomically resolved ultra-high-vacuum scanning tunnelling microscopy images. Second, we assume a polymer-SWNT distance (d) equal to 3.4 Å, as estimated from ab-initio calculations of the equilibrium distance between graphene and butane (widely used as a model for alkyl side chains).…”

“…Therefore, it does not explain why the sorting is selective for semiconducting versus metallic SWNTs. The geometrical model was devised based on the following: First, based on previous experimental observations, we assume that the polymer is able to wrap around a single SWNT 33,53 . Giulianini et al 33 reported a detailed experimental evidence of the regioregular poly(3-hexylthiophene) helical wrapping on CNTs by atomically resolved ultra-high-vacuum scanning tunnelling microscopy images.…”

“…Conjugated polymers, with extensive π-conjugated structures, have been reported to interact strongly with SWNTs 18,[30][31][32][33][34] . Although polymers, such as poly(9,9-dialkyl-fluorene) derivatives, were found to disperse sc-SWNTs 18 , making high-performance devices is challenging due to difficulty in removing these insulating polymers.…”