Chemistry Scholarships
ACES SOLAR CELL PROJECTS
Dye Sensitised Solar Cells and Devices (Four Scholarships)
Contacts: Leone Spiccia or Udo Bach or Doug MacFarlane
The conversion of solar energy into electricity is attracting more attention as non-renewable energy reserves diminish. Dye sensitised solar cells (DSSCs), first reported by Michael Grätzel in 1991, are one viable alternative to ‘classical’ photovoltaics. DSSCs consist of a nanostructured semiconductor film (e.g. ~10µm anatase titania), coated with a monolayer of photoactive dye (often a Ru(II) complex) and an electrolyte bearing a redox couple (e.g. I3-/I-, Fig.1). Absorption of a photon of light by the dye promotes an electron from a Ru d-orbital into a ligand π* orbital and into the semiconductor. It then migrates through the semiconductor into an external circuit and to a platinised counter electrode, which catalyses the conversion of I3- to I-. I- travels to the TiO2 surface where it reduces the dye to its original state. Repeated cycling generates a current. Efficiencies >10% have been achieved.
 
Figure 1. Schematics of a typical DSSC
DSSCs commonly consist of a TiO2. film sandwiched between two sheets of conductive glass (Fig. 1). We developed methods for depositing DSSCs on transparent polymers so that the cells can be made into flexible devices for easier commercial application. As polymers substrates degrade above 200°C, a major hurdle is the sintering temperature (~450°C) needed to prepare semiconductor films. We have been using the rapid and selective heating properties of microwave radiation to process TiO2 films deposited onto ITO coated polymer substrates.
We have also been examining approaches to increase cell efficiency by coating the semiconductor with a thin layer of an insulating oxide to minimise charge recombination effects. Work on new electrolyte materials has been accomplished and is an on-going project with successful collaborations with Monash Electrolytes Group as well as Prof. Grätzel at EPFL, Switzerland. Research is also focused on new redox couples which will be able to replace the standard I3-/I- used in the DSSCs.
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