Mohammed Khenfouch

Photoluminescence Quenching and Structure of Nanocomposite Based on Graphene Oxide Layers Decorated with Nanostructured Porphyrin

Nanocomposites based on few-layers graphene oxide (FGO) decorated with porphyrin nanorods (PN) were synthesized and the interfacial interaction between these two components was investigated by using scanning electron microscopy (SEM), photoluminescence spectroscopy, resonant Raman scattering and Fourier transform infrared (FT-IR) techniques. SEM showed good exfoliation of FGO and its successful interaction with the PN. The photoluminescence results showed an important interaction between FGO and PN resulting in a quenching of the photoluminescence of the PN-FGO composite. Resonant Raman with PN aggregates and FT-IR results revealed a π-π intermolecular interaction confirming the energy/charge transfer. Moreover, the investigation of X-ray diffraction confirmed the intercalation of PN in FGO and their disaggregation. The findings presented here are an important contribution to achieving the functionalization of graphene derivative surfaces with PN for various optoelectronic applications and particularly photovoltaic cells.

Growth and characterization of hybrid (HoGO/P3HT) graphene-based nanostructures for photovoltaic (PV) applications.

Herein, we present a comparative study between nanostructures of poly(3-hexylthiophene) (P3HT), Holmium-Graphene Oxide (HoGO) nanocomposite and hybrid HoGO/P3HT thin-film nanostructures in terms of structural morphological and spectroscopic properties. Specifically, the graphene based GO nanostructure was functionalized with rear earth ion Ho(III) to improve its mobility. Furthermore, semiconducting P3HT nanostructure was successfully grown with HoGO nanocomposite creating hybrid HoGO/P3HT nanostructure for energy materials. The nanostructures were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), (FTIR) and UV/VIS/NIR spectroscopy. The interaction between HoGO and HoGO/P3HT nanostructures is evidenced through substantial variations in nanoparticle morphologies. FTIR results provided the evidence of the presence of different types of carbon functionalities in the nanostructures. From the absorption spectra, growth of hybrid HoGO/P3HT nanostructure broadened the absorbance with a slight decrease in %. These nanostructures open a promising direction on growth of hybrids for photovoltaic applications because of their interesting optical properties.

Synthesis and opto-structural characterization of reduced graphene oxide and meso -tetrakis(4-phenylsulfonic-acid) porphyrin composites

The present paper aims to study the mixing of reduced graphene oxide (RGO) with meso-tetrakis(4-phenylsulfonic-acid)porphyrin [H4TPPS42−] via a covalent functionalization, through a facile synthesis process. The intermolecular interaction was investigated using scanning electron microscope, Raman scattering, Fourier transform infrared spectroscopy, X-ray diffraction. These techniques demonstrated a structural enhancement of the composite, a better conjugation system and the presence ofxa0component interaction at the molecular level. UV–Visible absorption, Steady state photoluminescence (PL) as well as time-resolved PL (TRPL) measurements were carried out to further elucidate the nature of electronic interaction between the components. Steady state PL quenching of the porphyrin is in favor of photoinduced electron and/or energy transfer to the RGO. The TRPL results exhibit a decrease in the exciton mean lifetime compared to that of porphyrin’s confirming the presence of significant interaction between H4TPPS42− and RGO, and corroborating the existence of new interbands leading to slower carrier recombination.

Charge Carrier Dynamics and pH Effect on Optical Properties of Anionic and Cationic Porphyrin–Graphene Oxide Composites

Composites of graphene oxide (GO) functionalized with Sn(V) tetrakis (4-pyridyl)porphyrin (SnTPyP2+) and meso-tetrakis(4-phenylsulfonic acid)porphyrin (H4TPPS42−) were prepared at different pH values.Successful synthesis of water-soluble stable suspension of GO–SnTPyP2+ and GO–H4TPPS42− was confirmed using various spectroscopic techniques, including scanning electronic microscopy (SEM), Raman spectroscopy, and ultraviolet–visible (UV–Vis) absorption. Variation of the pH was found to strongly influence the optical properties of the GO–SnTPyP2+ and GO–H4TPPS42− composites, as demonstrated by the UV–Vis absorption results. Steady-state photoluminescence (PL) and time-resolved PL (TRPL) results for both composites showed PL quenching and decrease in the exciton mean lifetime, suggesting strong excited-state interactions between the different components. Moreover, charge carrier dynamics study revealed that insertion of GO into both porphyrin derivatives led to faster mean lifetime for excitons with a slight advantage in the case of the cationic porphyrin–GO composite, making it a better choice for charge separation applications thanks to the higher efficiency of charge/energy transfer interactions.