p-type dye-sensitized solar cells

Coumarin 343 dye and a Fe-complex, previously shown to be a proton reduction catalyst were co-adsorbed to NiO. We could show that excitation of the dye led to rapid (< 50 ns) reduction of the catalyst. This shows that lateral surface electron transfer is possible, so that co-adsorption is a feasible way to construct photocatalytic NiO electrodes for hydrogen production.

Reference

• Light-Driven Electron Transfer between a Photosensitizer and a Proton-Reducing Catalyst Co-adsorbed to NiO. James M. Gardner et al., J. Am. Chem. Soc. 2012, 134, 19322-19325.

A Ru-NMI dyad on NiO showed substantial improvement of photovoltaic device properties compared to the corresponding Ru dye. We could show that the appended NMI acceptor unit was reduced, which substantially reduced the rate of recombination with NiO(+) and at the same time increased the rate of dyad regeneration by the Co(dtb)33+ electrolyte.

Reference

• Ru-based donor–acceptor photosensitizer that retards charge recombination in a p-type dye-sensitized solar cell. Jonathan C. Freys, et al.Dalton Trans. 2012, 41, 13105-13111.

We showed that dye-NiO charge recombination occurs in the Amrcus normal region, in spite of a large expected driving force, based on the NiO valence band potential value. We propose that recombination instead occurs to intra-bandgap states, which may be one reason for the rapid recombination reaction.

Reference

• Ultrafast recombination for NiO sensitized with a series of perylene imide sensitizers exhibiting Marcus normal behavior. Amanda L. Smeigh, et al. Chem. Commun. 2012 48, 678 – 680.