Fabrication and photovoltaic characterization of bio-sensitized solar cells using myoglobin-based sensitizers

Myoglobin (Mb), reconstituted zinc protoporphyrin-apomyoglobin (ZnMb), and eosin-modified ZnMb (EoZnMb) were used as photosensitizers to functionalize TiO ₂ nanocrystalline films for bio-sensitized solar-cell (BSSC) applications. For the Mb-sensitized SC, the poor cell performance was due to a reduction Fe(lll) - Fe(ll) that produces a photocurrent density of the device smaller than its unsensitized counterpart. The efficiencies of power conversion of both ZnMb and EoZnMb-sensitized SC were enhanced about ten times due to superior charge separation between TiO ₂ and the protein, and due to smaller current leakage between TiO2 and the electrolyte. The cell performances of the BSSC devices are discussed in terms of an equivalent-circuit model.