Dynamic properties of the excited states of oligo-N-vinylcarbazole functionalized with single walled carbon nanotubes

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

We present a systematic review of nanostructured organic materials, including synthesis methods, functionalization, and applications. First, we report the chemical and physical procedures used for preparing the polymer/carbon nanotube composites described in the literature over the last decade. We compare the properties of different polymer-based prototypes of organic nanocomposites functionalized with carbon nanotubes. Theoretical and experimental vibrational investigations provide evidence of the molecular structure describing the interaction between both components, showing that the allowed amount of carbon nanotubes and their dispersion states differ across polymers. Moreover, the nature of the solvent used in the preparation has a significant impact on the dispersion process. The integration of these materials in photovoltaic applications is discussed, where the impact of nanoparticles is evidenced through the correlation between experimental analyses and theoretical approaches based on density functional theory. Alterations in optical properties, evaluated from the absorption and luminescence process, are coherent with the solar spectrum, and a good distribution of donor/acceptor interpenetration was observed. In all cases, it was demonstrated that the performance improvement is physically related to the charge transfer from the organic matrix to the nanoparticles.

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

Polyaniline (PANI) was chemically doped and functionalized with single walled carbon nanotubes (SWCNTs). Various characterization methods were employed to study the structure and optical properties of PANI/SWCNTs nanocomposite, such as Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), optical absorption, and stationary photoluminescence. Additionally, a theoretical study using density functional theory calculations was also carried out. It has been demonstrated that the doping process may reduce the band gap without affecting the molecular structure, leading to a better compatibility with the solar spectrum. Moreover, the functionalization process with SWCNTs was able to significantly improve the properties of the resulting nanocomposite. The final interpenetrating network of PANI/SWCNTs exhibited an optical gap of nearly 2.28 eV, from which localized states induced by the charge transfer were created at nearly 1.70 eV. In addition, the resulting donor-acceptor network leads to a separation of electron holes pairs rather than their recombination, which can be used as an active layer in photovoltaic applications and a photocatalyst for advanced oxidation processes.

Structural and photophysical properties of PVK-F8BT copolymer thin films, with single walled carbon nanotubes: Synthesis, characterization and modeling

The nanocomposite material was elaborated (developed) by mixing of the PVK-F8BT copolymer onto the single walled carbon nanotubes SWCNTs. The new composites were prepared with various weight concentrations of SWCNTs (0.75%, 1.5% and 3%). Different experimental analyses were performed to examine their morphological features and their optical and vibrational spectroscopy behaviors as a function of the concentration of short single-walled carbon nanotubes. Π-staking interaction and the functionalization process between the copolymer and the SWCNTs have a considerable effect on the vibratory and photoemissive properties of the copolymer matrix. Scanning electron microscopy (SEM) and transmission (TEM) were used. Then, Raman scattering and steady state and time-resolved photoluminescence (PL) and (TRPL) measurements were used to study the evolution of spectroscopic characteristics and optical properties of the PVK-F8BT/SWCNTs composites. An extinction effect of PL and a decrease in the average life of the exciton time was observed. These indicated the processing of a charge transfer leading to exciton dissociations to the SWCNTs matrix. The results, also supported by DFT-based modeling method have proven a strong evidence of the functionalization and the charge transfer between the SWCNTs and the PVK-F8BT copolymer and predicted equally a correlation of structural properties.