Browsing by Subject "BODIPY"

Now showing 1 - 3 of 3
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    Driven by Light: An Ultrafast Look into the Bright Future of Photosensitizers
    (2024-04) Schaffner, Jacob
    This thesis investigates various strong light-absorbing molecules that have potential applications in furthering our progress into replacing fossil fuels with clean energy resources and remediating harmful chemicals in the environment. The research presented in this thesis employs a range of spectroscopic techniques, complemented with computational predictions, to characterize the light absorption and excited state dynamics of newly developed chromophores that have shown promise in these various applications. Chapter 3 investigates a BODIPY-fullerene dyad designed to be used in organic photovoltaics as a triplet sensitizer to form longer-lived excitons. This triplet sensitization occurs via a ping-pong energy transfer mechanism between the BODIPY and fullerene, resulting in a long-lived BODIPY triplet (>1 µs). Chapters 4 and 5 investigate the MB-DIPY chromophore that could potentially displace fullerene as a strong and more versatile electron acceptor in organic photovoltaics. In Chapter 4, the redox potentials and photophysics of four MB-DIPY analogs are explored. The MB-DIPYs had comparable reduction potentials to fullerene and demonstrated efficient intersystem crossing to form long-lived triplet states (>10 µs). In Chapter 5, the MB-DIPY is functionalized with ferrocene, a strong electron donor, and demonstrated sub-ps charge-transfer from the ferrocene to the MB-DIPY followedby charge recombination in 12 ps. Chapters 6 and 7 investigate the Rh-Ga and Co-Ga heterobimetallic photocatalysts that can access challenging bonds via a photoredox mechanism. The excited state nature of these photocatalysts is first explored in Chapter 6. The results were consistent with the naked anionic catalyst being the active participant in the photocatalytic cycle. Chapter 7 investigates the reactivity of the photocatalysts with a chloroadamantane substrate. The results suggested that the substrate binds to the anionic rhodium photocatalyst and that the photocatalytic reactivity is not diffusion-limited. In contrast, the anionic cobalt catalyst was converted into the chlorinated precatalyst upon the addition of the substrate, demonstrating that the chemical reactivity of the rhodium and cobalt photocatalysts differ with this substrate.
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    Excited State Dynamics of Model Photovoltaic Materials
    (2021-01) Swedin, Rachel
    Investigation of new materials for potential use in organic photovoltaics and dye-sensitized solar cells found unique systems that maintained a relatively long-lived (ns and longer) charge separated state or energy transferred state. The molecules studied in this thesis show promise for use in organic photovoltaics or dye-sensitized solar cells. Further studies in the solid state of these molecules are required to determine their efficiency andtheir ability to function in a photovoltaic module. Chapter 1 gives an overview of the status of energy usage in the world and how photovoltaics fit into it. This chapter also explains the key scientific concepts used for interpretation of experiments. Chapter 2 goes through an in-depth description of the experimental techniques and processes used in this thesis. Chapter 3 examines a thiophene- and furan-based dye when in an equimolar mixture with varying sizes of ZnO nanoparticles. A long-lived charge-separated state is found when both dyes are coordinated to the ZnO nanoparticles, showing a spectral signature of electron transfer from the thiophene and furan-based dyes to the ZnO. The charge-separated state exists beyond the time delay for the experiment (3.5 ns), indicating promise for a dye-sensitized solar cell containing these molecules. Investigation into BODIPY molecules for use as an absorber in organic photovoltaics begins with Chapter 4. In Chapter 4, the electron transfer properties from the catechol group to multiple BODIPY derivatives are identified. It is found that rapid electron transfer from the catechol, linked at the boron hub of the BODIPY, to the BODIPY deactivated the excited state from further interaction with surrounding systems, a detail missed in other publications with the same catechol attached to the boron-hub of BODIPY. This conclusion was carried into Chapter 5 where use of the catechol to bridge the fullerene to the BODIPY leads to no interaction with fullerene. This is because the catechol rapidly transferred an electron to the BODIPY and deactivated further electron transfer. Ferrocene added to the BODIPY-fullerene molecule out-competed the catechol for electron transfer to the BODIPY derivative, making a ~200 ps lived electron transfer state. The catechol linker is not the only bridge studied between a BODIPY derivative and fullerene. A pyridone ring connected at the alpha and position of the BODIPY is also used to bridge to fullerene. In this study the fullerene functioned as a triplet sensitizer for the BODIPY, leading to a microsecond lived BODIPY triplet. Lastly, a zinc phthalocyanine is studied when coordinated to a BODIPY derivative and fullerene through a pyridine ring. Spectral and redox evidence shows electron transfer from the phthalocyanine occurred, soon followed by recombination. Energy transfer from the BODIPY to the phthalocyanine was also present, followed by electron transfer back to the BODIPY before decaying to the ground state.
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    Synthesis and Characterization of C60_aza_BODIPY
    (2014) Hoover, Brittany; Nemykin, Viktor