Ali Yassin - Academia.edu (original) (raw)
Papers by Ali Yassin
Chemistry of Materials, 2015
Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and high resol... more Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) experiments, indicate that molecular junctions can be achieved between non-carbon-coated LiFePO 4 (LFP) and multi-wall carbon nanotubes (MWCNT) using a thiophene-based conjugated system which was designed to selectively functionalize these two different types of surface. The strategy enables the architecturing of the cathode electrode of lithium batteries leading to a vast improvement in the component intermixing, which results in the individual MWCNT being nano-contacted at the surface of LFP grains. This advancement leads to much higher specific capacity, especially at high charge/discharge rates, for undensified electrodes of 2 mA h cm -2 , for which the electronic wiring of the electroactive material is a critical issue. Furthermore, thanks to molecular junctions, better capacity retention comparable to that of carbon coated LiFePO 4 (LFPC) electrodes could be achieved. These results are expected to trigger the development of novel electron transport engineering methods, of special interest for industry-relevant thick battery electrodes.
![Research paper thumbnail of Synthesis and Chain-Length Dependence of the Electronic Properties of pi-Conjugated Dithieno[3,2-b:2 ',3 '-d]pyrrole (DTP) Oligomers](https://attachments.academia-assets.com/40537954/thumbnails/1.jpg)
](Macromolecular Rapid Communications, 2010
N-(2-ethylhexyl)dithieno[3,2-b:2 0 ,3 0 -d]pyrrole has been prepared and its dimer and trimer hav... more N-(2-ethylhexyl)dithieno[3,2-b:2 0 ,3 0 -d]pyrrole has been prepared and its dimer and trimer have been synthesized by Stille coupling. The electrochemical and optical properties of these compounds have been investigated by cyclic voltammetry, UV-Vis, and fluorescence emission spectroscopies. The obtained results show that these strongly luminescent compounds can be oxidized into stable cation radical and dication state. The analysis of the chain length dependence of the electronic properties indicates that the predicted bandgap of an ideal polymer chain should be considerably smaller than the experimental results reported until now. This difference is discussed in terms of reactivity of the dithieno[3,2-b:2 0 ,3 0 -d]pyrrole (DTP) unit.
Synthetic Metals, 2008
The synthesis of a fluorene derivative bearing a fluorescein moiety is described together with it... more The synthesis of a fluorene derivative bearing a fluorescein moiety is described together with its anodic electropolymerization in presence of various amount of fluorene. Both polymers and monomers can be used as pH indicators in water and other medium. The fluorescence and absorption properties in function of the pH are presented and compared with those of fluorescein. In the excited state, the Fluorescein-fluorene monomer appears to be a stronger acid than fluorescein.
Solar Energy Materials and Solar Cells, 2011
Three conjugated compounds based on carbazole, cyclopentadithiophene and dithienopyrrole substitu... more Three conjugated compounds based on carbazole, cyclopentadithiophene and dithienopyrrole substituted by branched alkyl chains have been synthesized by the Knoevenagel condensation of malonodinitrile with the appropriate dicarboxaldehyde. Electronic properties of the target compounds have been analyzed in solution by UV-vis absorption spectroscopy and cyclic voltammetry and their potentialities as a donor material in donor-acceptor heterojunction solar cells have been evaluated in bilayer devices involving both solution processed or vacuum deposited donor layers and thermally evaporated fullerene C 60 as an acceptor.
New Journal of Chemistry, 2012
A symmetrical donor-acceptor-donor D-A-D system built by connecting two dithienopyrrole donor blo... more A symmetrical donor-acceptor-donor D-A-D system built by connecting two dithienopyrrole donor blocks to a central electron acceptor obtained by dimerization of 3-alkoxy-4-cyanothiophene has been synthesized and characterized. The compound combines a high photoluminescence efficiency with a broad absorption spectrum in the solid state and a band gap of 1.70 eV. A preliminary evaluation of the potentialities of this type of compound as donor material in bulk heterojunction solar cells using PC 61 BM as electron acceptor is presented.
New Journal of Chemistry, 2013
Two D-A-D systems involving benzofuran and dithienopyrrole as donor blocks and isoindigo as an ac... more Two D-A-D systems involving benzofuran and dithienopyrrole as donor blocks and isoindigo as an acceptor unit have been synthesized and their electronic properties have been characterized by UV-Vis absorption spectroscopy and cyclic voltammetry. A preliminary evaluation of these compounds as active material in organic solar cells shows that the presence or absence of substitution at the nitrogen atom of indigo strongly affects the properties of the material and thus the performances of the resulting solar cells.
Dyes and Pigments, 2009
The synthesis, crystal structure, electrochemical and optical properties of a novel blue emitting... more The synthesis, crystal structure, electrochemical and optical properties of a novel blue emitting ladder pentaphenylene are reported and compared with those of its 3pÀ2 spiro parent, in order to study the effect of the spiro-linked fluorene rings. Anodic oxidation of the novel compound results via electropolymerization, in the formation of an electroactive material that displays interesting electrochemical and optical properties.
Chemistry of Materials, 2015
Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and high resol... more Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) experiments, indicate that molecular junctions can be achieved between non-carbon-coated LiFePO 4 (LFP) and multi-wall carbon nanotubes (MWCNT) using a thiophene-based conjugated system which was designed to selectively functionalize these two different types of surface. The strategy enables the architecturing of the cathode electrode of lithium batteries leading to a vast improvement in the component intermixing, which results in the individual MWCNT being nano-contacted at the surface of LFP grains. This advancement leads to much higher specific capacity, especially at high charge/discharge rates, for undensified electrodes of 2 mA h cm -2 , for which the electronic wiring of the electroactive material is a critical issue. Furthermore, thanks to molecular junctions, better capacity retention comparable to that of carbon coated LiFePO 4 (LFPC) electrodes could be achieved. These results are expected to trigger the development of novel electron transport engineering methods, of special interest for industry-relevant thick battery electrodes.
Macromolecular Rapid Communications, 2010
N-(2-ethylhexyl)dithieno[3,2-b:2 0 ,3 0 -d]pyrrole has been prepared and its dimer and trimer hav... more N-(2-ethylhexyl)dithieno[3,2-b:2 0 ,3 0 -d]pyrrole has been prepared and its dimer and trimer have been synthesized by Stille coupling. The electrochemical and optical properties of these compounds have been investigated by cyclic voltammetry, UV-Vis, and fluorescence emission spectroscopies. The obtained results show that these strongly luminescent compounds can be oxidized into stable cation radical and dication state. The analysis of the chain length dependence of the electronic properties indicates that the predicted bandgap of an ideal polymer chain should be considerably smaller than the experimental results reported until now. This difference is discussed in terms of reactivity of the dithieno[3,2-b:2 0 ,3 0 -d]pyrrole (DTP) unit.
Synthetic Metals, 2008
The synthesis of a fluorene derivative bearing a fluorescein moiety is described together with it... more The synthesis of a fluorene derivative bearing a fluorescein moiety is described together with its anodic electropolymerization in presence of various amount of fluorene. Both polymers and monomers can be used as pH indicators in water and other medium. The fluorescence and absorption properties in function of the pH are presented and compared with those of fluorescein. In the excited state, the Fluorescein-fluorene monomer appears to be a stronger acid than fluorescein.
Solar Energy Materials and Solar Cells, 2011
Three conjugated compounds based on carbazole, cyclopentadithiophene and dithienopyrrole substitu... more Three conjugated compounds based on carbazole, cyclopentadithiophene and dithienopyrrole substituted by branched alkyl chains have been synthesized by the Knoevenagel condensation of malonodinitrile with the appropriate dicarboxaldehyde. Electronic properties of the target compounds have been analyzed in solution by UV-vis absorption spectroscopy and cyclic voltammetry and their potentialities as a donor material in donor-acceptor heterojunction solar cells have been evaluated in bilayer devices involving both solution processed or vacuum deposited donor layers and thermally evaporated fullerene C 60 as an acceptor.
New Journal of Chemistry, 2012
A symmetrical donor-acceptor-donor D-A-D system built by connecting two dithienopyrrole donor blo... more A symmetrical donor-acceptor-donor D-A-D system built by connecting two dithienopyrrole donor blocks to a central electron acceptor obtained by dimerization of 3-alkoxy-4-cyanothiophene has been synthesized and characterized. The compound combines a high photoluminescence efficiency with a broad absorption spectrum in the solid state and a band gap of 1.70 eV. A preliminary evaluation of the potentialities of this type of compound as donor material in bulk heterojunction solar cells using PC 61 BM as electron acceptor is presented.
New Journal of Chemistry, 2013
Two D-A-D systems involving benzofuran and dithienopyrrole as donor blocks and isoindigo as an ac... more Two D-A-D systems involving benzofuran and dithienopyrrole as donor blocks and isoindigo as an acceptor unit have been synthesized and their electronic properties have been characterized by UV-Vis absorption spectroscopy and cyclic voltammetry. A preliminary evaluation of these compounds as active material in organic solar cells shows that the presence or absence of substitution at the nitrogen atom of indigo strongly affects the properties of the material and thus the performances of the resulting solar cells.
Dyes and Pigments, 2009
The synthesis, crystal structure, electrochemical and optical properties of a novel blue emitting... more The synthesis, crystal structure, electrochemical and optical properties of a novel blue emitting ladder pentaphenylene are reported and compared with those of its 3pÀ2 spiro parent, in order to study the effect of the spiro-linked fluorene rings. Anodic oxidation of the novel compound results via electropolymerization, in the formation of an electroactive material that displays interesting electrochemical and optical properties.