Designing outer-sphere redox shuttles and investigating efficiency limiting electron transfer processes for the advancement of dye sensitized solar cells

Dye sensitized solar cells (DSSCs) are considered as a promising alternative technology to harness the solar energy cost-effectively for the purpose of tackling the energy crisis and climate change. The complex but also unique construction of DSSCs offers various designs utilizing abundant and cheap materials. This dissertation focuses on the design and development of one important component in DSSCs, redox shuttles. A primary goal presented here is exploring alternative outer-sphere redox shuttles which are able to strike a balance between the two efficiency determining electron transfer processes in DSSCs, dye regeneration and electron recombination. Utilizing Marcus theory allows us to investigate the effects of the two processes on overall efficiency and introduce new route for redox shuttles design, i.e. introduction of low spin cobalt-based outer-sphere redox shuttles. Several routes to design low spin cobalt based redox shuttles are discussed. The systematic study of regeneration and recombination in terms of Marcus theory using these redox shuttles is also presented which illustrated the effect of reorganization energy and driving force evolving from the redox shuttle molecular design.