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Synthèse et caractérisation de nouveaux complexes Fe-NHC applicables en cellule solaire DSSC

Abstract : This thesis is part of a current concern and high interest research field, which is the development of new photoactive complexes using abundant metals to replace noble metals in renewable energy devices. Novel families of potential sensitizers for DSSC (Dye-sensitized solar cells) based on iron and tridentate pyridyl-carbene ligands (FeNHC) have been prepared and characterized. The aim, besides the application aspect for energy, is to increase the understanding of the structure-property relationships in Fe-NHC homoleptic complexes carrying pyridyl-bisimidazolylidene ligands by modification of the central core, anchoring group and coordination geometry. Once synthesized, the complexes were submitted to various photophysical, electrochemical and theoretical characterizations. A new MLCT excited state lifetime record was obtained with a pyrazine-based complexes (32 ps). The geometric optimization, which means the design of ligands to obtain an ideal octahedral coordination geometry to induce a strong ligand field was studied. X-ray diffraction measurements attested that the desired complexes were obtained by increasing the distance between the pyridine core and the lateral carbenes. This modification induces a bathochromic shift, but the electronic conjugation as well as the rigidity of the complexes remain to be optimized further. We have also developed a novel synthetic route for introducing π-extended anchoring groups in order to limit the charge recombination after the injection into the TiO2 semiconductor. The efficiency of the DSSC cells was optimized by the incorporation of a new MgI2 additive in the electrolyte composition which led to an unprecedented efficiency of 0.5% for an iron complex. Finally, this thesis offers new synthetic tools for the design of FeII-NHC complexes with extended excited state lifetimes and represents a further step in the understanding of the photophysical processes operated within this type of iron complexes.
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Submitted on : Friday, June 19, 2020 - 10:41:22 AM
Last modification on : Tuesday, January 4, 2022 - 6:47:46 AM

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  • HAL Id : tel-02874783, version 1


Mohamed Darari. Synthèse et caractérisation de nouveaux complexes Fe-NHC applicables en cellule solaire DSSC. Chimie. Université de Lorraine, 2019. Français. ⟨NNT : 2019LORR0318⟩. ⟨tel-02874783⟩



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