Photoexcitations in composites of poly(paraphenylene vinylene) and single-walled carbon nanotubes

Abstract

Absorption and photoluminescence ͑PL͒ studies have been carried out on pristine standard poly͑paraphenylene vinylene͒ PPV and a series of PPV-single-walled carbon nanotubes ͑SWNT͒ composite films. Drastic changes in the PL and absorption spectra are observed with the increase of the SWNT fraction. A model is presented which is able to explain quantitatively the modification of absorption spectra, and particularly the new features in PL spectra as a function of SWNT percentages in the films. We provide evidence for strong electronic interaction between SWNT and the PPV polymer precursor precluding the complete thermal conversion of the polymer matrix.

About Grafting of Single-Walled Carbon Nanotubes on the Oligo-N-Vinyl Carbazole and Copolymer Involving N-Vinylcarbazole and Hexylthiophene

“…Thus, at the blue side of the spectrum (wavelength lower than 400) relative to the PVK polymers, bands are nearly the same. However, the band at 430 nm shows a sudden decrease when adding SWNTs and undergoes a continuously blueshiftwing, reflecting that there is a shortness of the effective conjugation length of these blocks (Wéry et al, 2003). Although, there is no significant changes observed in optical absorption spectra when increasing SWNTs weight concentration due to the already reached percolation threshold, the large amount of SWNTs either in grafted or not, or in isolated or bundled forms can influences the excitated states of the resulting composite (Massuyeau et al, 2007).…”

Photomodulation spectrum of phenyl-substituted ladder-type poly(para-phenylene) under hydrostatic pressure

“…The vibrational properties of the molecules under compression could be revealed from the Raman spectrum. Mulazzi et al calculated the Raman spectra of organic material with different conjugated lengths under pressure, which indicated that the electronic states of longer conjugated-length segments had stronger interaction with the mode of the side chain [25,26]. The study of Raman spectrum under pressure has shown that the higher planarity in structure of Ph-LPPP at higher pressure [27] such that electrons are easier to transit along the backbone and to produce electronic delocalization.…”

Composites Based on Conducting Polymers and Carbon Nanotubes

“…This is a consequence of a structured wrapping of the polymer onto the nanotube lattice, and a signature of strong noncovalent binding [204,205]. Another method of preparation of composites based on SWNTs and PPV was reported by S. Lefrant's group [206,207]. The materials were prepared by mixing SWNTs at different weight concentrations in the soluble sulfonium polyelectrolyte precursor of PPV, with sonication.…”

“…In addition, photoluminescence spectra were strongly modified, in both intensity and shape, with the appearance of new bands in the blue range. This was interpreted as the formation of short conjugated segments that dominate long segments in composite materials [206,207].…”