Ruthenium-Based Dyes for Dye Solar Cells

Material Matters 2008, 3.4, 99.

Dye solar cells (DSCs) are third generation solar cells with the promise of high efficiency combined with low production costs. While present day DSCs provide light-to-electricity conversion of up to 11%, significant further improvement is envisaged through optimized materials and novel cell and module architectures.

In dye sensitized solar cells, the dye is one of the key components for high-power conversion efficiencies. In recent years, considerable developments have been made in the engineering of the dye structure to enhance the performance of the system.

Particularly interesting are the amphiphilic homologues of the pioneering ruthenium based N-3 dye, for example, Z-907 (Prod. No. 703168). The amphiphilic dyes display several advantages over the N-3 dye:

1. a higher ground state pKa of the binding moiety thus increasing electrostatic binding onto the TiO₂ surface at lower pH values
2. decreased charge on the dye, attenuating electrostatic repulsion between adsorbed dye units and thereby increasing dye loading
3. increased stability of solar cells towards water-induced dye desorption
4. oxidation potential of these complexes is cathodically shifted compared to that of the N-3 sensitizer, which increases the reversibility of the ruthenium III/II couple, leading to enhanced stability.