Correlation between microstructures and optical properties of polyaniline/single‐walled carbon nanotubes composites

Abstract

The polyaniline was doped with sulfonic acid and functionalized with single-walled carbon nanotubes. The effects of single-walled carbon nanotubes (SWCNTs) inserting and thermal annealing at T = 393 K, during 24 h are carried out by optical and structural study. Structural characterizations of D-polyaniline (PANI) or D-PANI/SWCNTs compounds at both pristine and annealed states were obtained by Fourier Transform infrared analysis and scanning and transmission electron microscopies. Optical parameters including absorption coefficient, optical transition type, energy gaps, skin depth, and extinction coefficient have been also elucidated from optical absorption measurements. Moreover, the characteristics of the localized states introduced either by SWCNTs adding and/or annealing temperature are carried out. By referring to the starting material, the direct (indirect) optical band gap was found to be reduced from 3.91 (3.75) to 2.35 (2.24) eV, after SWCNTs inserting and annealing. Moreover, new localized states having a band width of 390 meV are created at 1.25 eV. The SWCNTS dispersion quality on the organic matrix and the PANI self-crosslinking lead to the charge transfer and the resulting interpenetrating network can be used as active layers for organic solar cells. POLYM. COMPOS., 40: E821-E831, 2019.

Polyaniline: Doping and Functionalization with Single Walled Carbon Nanotubes for Photovoltaic and Photocatalytic Application

“…However, both narrow intermediate peaks are, in our opinion, attributed to the ring opening and chain scission resulting from the already cross-linked chains under temperature elevation, as suggested in the case of PANI polymers [ 60 , 61 ]. The same behavior has been also evidenced in our previous work for annealed PANI/SWCNTs composite [ 62 ].…”

Polymer/Carbon Nanotube Based Nanocomposites for Photovoltaic Application: Functionalization, Structural, and Optical Properties

“…Vibrational and optical behaviors of the hybrid material after annealing were analyzed in a previous study [ 132 ]. Interpretation of changes in FTIR spectra has shown the grafting and self-cross-linking of PANI moieties [ 133 , 134 ].…”

“…These chemical environments could not be the consequence of CNT insertion (the same line shape appears with and without CNTs). These additional bands are typically coherent with self-cross-linking ( Figure 17 (2)), such as benzene ring para- and ortho-link, to nitrogen atoms [ 132 ].…”

“…After annealing at 393 K, new absorption bands are created at λ max = 570 nm and at λ max = 792 nm, respectively, for doped and functionalized states [ 132 ]. These new optical features support the presence of a quinoidal ring and agree well with the self-cross-linking process [ 135 , 136 ].…”

“…The large value after annealing is the consequence of well-dispersed nanoparticles, involving good compatibility between the diffusion length and CNT repartition. A microscopic study mentions that bundled CNTs before annealing became relatively dispersed and homogeneously distributed, with the repartition size varying from 3 to 8 nm [ 132 ]. At the molecular scale, annealing leads to partially dispersed and oriented SWCNTs in cross-linked PANI.…”