Browsing by Author "McCree-Grey, J"

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    Dye⋯TiO2 interfacial structure of dye-sensitised solar cell working electrodes buried under a solution of I−/I3− redox electrolyte
    (Royal Society of Chemistry, 2017-07-27) McCree-Grey, J; Cole, JM; Holt, SA; Evans, PJ; Gong, Y
    Dye-sensitised solar cells (DSCs) have niche prospects for electricity-generating windows that could equip buildings for energy-sustainable future cities. However, this ‘smart window’ technology is being held back by a lack of understanding in how the dye interacts with its device environment at the molecular level. A better appreciation of the dye⋯TiO2 interfacial structure of the DSC working electrodes would be particularly valuable since associated structure–function relationships could be established; these rules would provide a ‘toolkit’ for the molecular engineering of more suitable DSC dyes via rational design. Previous materials characterisation efforts have been limited to determining this interfacial structure within an environment exposed to air or situated in a solvent medium. This study is the first to reveal the structure of this buried interface within the functional device environment, and represents the first application of in situ neutron reflectometry to DSC research. By incorporating the electrolyte into the structural model of this buried interface, we reveal how lithium cations from the electrolyte constituents influence the dye⋯TiO2 binding configuration of an organic sensitiser, MK-44, via Li+ complexation to the cyanoacrylate group. This dye is the molecular congener of the high-performance MK-2 DSC dye, whose hexa-alkyl chains appear to stabilise it from Li+ complexation. Our in situ neutron reflectometry findings are built up from auxiliary structural models derived from ex situ X-ray reflectometry and corroborated via density functional theory and UV/vis absorption spectroscopy. Significant differences between the in situ and ex situ dye⋯TiO2 interfacial structures are found, highlighting the need to characterise the molecular structure of DSC working electrodes while in a fully assembled device. © Royal Society of Chemistry 2020
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    Reflectometry as a tool for studying dye molecule orientation in dyesensitised solar cells (DSCs)
    (Australian Institute of Physics, 2014-02-06) McCree-Grey, J; Cole, JM
    With world energy demand set to double by 2050, it is imperative that clean, efficient and cost-effective alternatives to fossil fuels are developed. Dye-sensitised Solar Cells (DSCs) are a positive step towards a low-cost, mass-producible source of photovoltaic power, with laboratory devices now capable of reaching efficiencies of up to 15%. Typical DSCs consist of a dye-sensitised semiconductor surrounded by a redox electrolyte and sandwiched between two transparent, conductive substrates. The dye is the principle light adsorber, injecting photo-excited electrons into the semiconductor conduction band and giving rise to the cells electrical characteristics. The electron injection is enabled by the dye’s physical and electrostatic interaction with the semiconductor surface and the nature of this interaction can have a major impact on the cell’s performance. Many dye species have been trialled in DSCs in efforts to improve these characteristics, however, the fundamental properties of dye orientation and molecular packing on the semiconductor surface remain widely unknown. X-ray reflectometry (XRR) has already been successfully applied to this field of DSCs but application of reflectometry to a fully functioning DSC has still yet to be realised. This presentation will discuss results obtained using X-ray reflectometry to study the dye-orientations and packing densities for a number of different dye systems. Further discussion on the development of procedures to then apply neutron reflectometry to study a fully functioning dye-sensitised solar cell will then be examined.