Minimizing energy losses in dye-sensitized solar cells using coordination compounds as alternative redox mediators coupled with appropriate organic dyes

Abstract

To further boost the efficiency of dye-sensitized solar cells, a correct evaluation of the real limitations of this type of solar cell should be conducted. From a simple analysis of the photovoltaic data found in the literature, it is evident that the V oc decrease, through energy losses, seems to be the most crucial factor diminishing the overall system efficiency. In particular, losses arising from the regeneration of the dye by the iodide/triiodide redox mediator are huge. The most convenient manner to recuperate these losses is the use of alternative redox mediators with more positive redox potentials than that of the iodide-based shuttle. Among various types of redox active compounds, ferrocene/ferrocenium, Cu +/ 2+, and Co 2+/3+ complexes are found to be the most effective in solar cells and the obtained efficiencies of more than 12% clearly show that a breakthrough is close, paving revolutionary roads towards making new records. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.