Browsing by Subject "fullerene"

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    Synthesis, Characterization, and Investigation of Non-covalent Interactions Between Novel Pyrene-appended Porphyrins and C60
    (2015-09) Wertish, Anthony
    Two different sets of novel pyrene-containing porphyrins were synthesized. The first set, which consists of asymmetric A3B1 and A2B2 porphyrins, was synthesized by the condensation of t-butylphenyl dipyrromethane and newly reported 4-(1-pyrenylmethoxy)benzaldehyde. The second set consists of asymmetric A3B1 and A2B2 porphyrins, which were synthesized by condensation of the dipyrromethane of the newly reported 4-(1-pyrenylmethoxy)benzaldehyde and 1-ferrocenecarboxaldehyde. All four porphyrins were fully characterized by UV-Vis-NIR spectroscopy, NMR spectroscopy, MCD spectroscopy and high-resolution mass spectrometry. Fluorescence spectroscopy studies were performed to qualitatively observe the interactions of the porphyrins with C60 fullerene. It was observed that C60 significantly quenches the fluorescence of pyrene, thus blocking fluorescence, suggesting there is a large amount of interaction between pyrene and C60. DFT and TDDFT calculations were performed in order to further investigate the electronic structure and nature of the excited states of the target porphyrins by first optimizing the equilibrium geometries at the DFT level using the CAM-B3LYP exchange-correlation functional and furthermore using TDDFT. Transient absorption spectroscopy data is being analyzed to elucidate the electron transfer properties of the new porphyrins.
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    Vibrational Sum Frequency Generation Spectroscopy (VSFG) Studies of Organic Electronic Molecules
    (2016-12) Sohrabpour, Zahra
    This dissertation describes the application of vibrational sum frequency generation (VSFG) spectroscopy to the study of molecules utilized in organic solar cells (OSC). Two known molecules were chosen for this study, sexithiophene (6T) and fullerene (C60). In the first study VSFG is employed to probe C60 on dielectric surfaces. The SFG activity of this centrosymmetric molecule (theoretically SFG silent) is hypothesized to be from the surface perturbation, resulting an interruption in the symmetry and causing SFG activity. This suggestion is confirmed by experimental VSFG and calculations as well. This study also offers a unique method for estimating surface charge. In the second study the orientation of 6T molecules at different thicknesses is investigated using a combination of VSFG spectroscopy and atomic force microscopy (AFM). The results confirm previous X-ray studies that, 6T has two very different thickness-dependent orientations. At submonolayer thickness, 6T has an edge-on orientation which changes to an end-on orientation with increase in thickness. Additionally, using VSFG and the thin film interference model it is demonstrated that the orientation of 6T molecules are not the same on the two interfaces, 6T/air and substrate/6T. This study highlights the capability of SFG as a surface probe technique to analyze submonolayer thicknesses. The last study showcases electrical measurements on organic photovoltaic devices. The effect of different donor and acceptor materials and donor/acceptor modification through positioning a layer of a modifier molecule at the interface is examined.