Structure/function relationships in dyes for solar energy conversion: a two-atom change in dye structure and the mechanism for its effect on cell voltage.
Recombination between injected electrons and iodine limits the photovoltage in dye-sensitized solar cells (DSSCs). We have recently suggested that many new dye molecules, intended to improve DSSCs, can accelerate this reaction, negating the expected improvement (J. Am. Chem. Soc. 2008, 130, 2907). Here we study two dyes with only a two-atom change in the structure, yet which give different V(oc)s. Using a range of measurements we show conclusively that the change in V(oc) is due solely to the increase in the recombination rate. From the structure of the dyes, and literature values for iodine binding of similar compounds, we find that it is very likely that the change in V(oc) is due solely to the difference in iodine binding at the site of the two-atom change. Using the large amount of literature on iodine complexation, we suggest structures for dyes that might show improved V(oc).
O'Regan
Brian C
BC
Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom. b.oregan@imperial.ac.uk
Walley
Kate
K
Juozapavicius
Mindaugas
M
Anderson
Assaf
A
Matar
Farah
F
Ghaddar
Tarek
T
Zakeeruddin
Shaik M
SM
Klein
Cédric
C
Durrant
James R
JR