J. Phys. Chem. C 2009, 113, 3881–3886
3881
Effect of Anchoring Group on Electron Injection and Recombination Dynamics in Organic Dye-Sensitized Solar Cells Joanna Wiberg,† Tannia Marinado,‡ Daniel P. Hagberg,§ Licheng Sun,§ Anders Hagfeldt,‡,| and Bo Albinsson*,† Department of Chemical and Biological Engineering/Physical Chemistry, Chalmers UniVersity of Technology, 412 96 Go¨teborg, Sweden, and Inorganic and Organic Chemistry, Chemical Science and Engineering, Center of Molecular DeVices, Royal Institute of Technology, 100 44 Stockholm, Sweden ReceiVed: NoVember 18, 2008; ReVised Manuscript ReceiVed: January 12, 2009
In the field of dye-sensitized solar cells, the number of different sensitizing dyes is increasing rapidly. To produce low-cost dyes, much work is being directed toward synthesizing all-organic, ruthenium-free dyes with high extinction coefficients and broad absorption bands with large solar spectrum overlap. One of the best dyes, the polyene-diphenylaniline dye D5L2A1, has a rather blue absorption with an IPCE onset at around 650 nm, but it still has an energy conversion efficiency of almost 6%. To increase the overlap with the solar spectrum, the cyanoacrylic acid anchoring group was changed to rhodanine-3-acetic acid in complex D5L2A3. This gave an IPCE onset at around 750 nm, but unfortunately, it also decreased the overall efficiency to a modest 1.7%. By femtosecond transient absorption, we show that the electron injections into TiO2 for the two dyes are ultrafast and indistinguishable with our time resolution (
