The ideal driving force for dye regeneration is an important parameter for the design of efficient dye-sensitized solar cells. Here, nanosecond laser transient absorption spectroscopy was used to measure the rates of regeneration of six organic carbazole-based dyes by nine ferrocene derivatives whose redox potentials vary by 0.85 V, resulting in 54 different driving-force conditions. It was found that the reaction follows the behavior expected for the Marcus normal region for driving forces below 29 kJ mol(-1) (Delta E = 0.30 V). Driving forces of 29-101 kJ mol(-1) (Delta E = 0.30-1.05 V) resulted in similar reaction rates, indicating that dye regeneration is diffusion controlled. Quantitative dye regeneration (theoretical regeneration yield 99.9 ) can be achieved with a driving force of 20-25 kJ mol(-1) (Delta E approximate to 0.20-0.25 V).
Daeneke, T., Mozer, A. J., Uemura, Y., Makuta, S., Fekete, M., Tachibana, Y., Koumura, N., Bach, U., & Spiccia, L. (2012). Dye regeneration kinetics in dye-sensitized solar cells. Journal of the American Chemical Society, 134(41), 16925 - 16928. https://doi.org/10.1021/ja3054578