Electron Lifetime in Dye-Sensitized Solar Cells Fabricated with Various Dyes: Comparison Between Porphyrin Dyes and Metal Free Organic Dyes

  • Mr Kenji Sunahara, Department of Fine Materials Engineering, Shinshu University, Japan
  • Masanori Miyashita, Department of Fine Materials Engineering, Shinshu University, Japan
  • Dr George Tsekouras, ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Australia
  • Dr Gordon Wallace, ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Australia
  • Dr Pawel Wagner, ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Australia
  • Dr David Officer, ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Australia
  • Dr Wayne Campbell, Nanomaterials Research Centre, IFS-Chemistry, Massey University, New Zealand
  • Dr Shogo Mori, Department of Fine Materials Engineering, Shinshu University, Japan
  • Attila Mozer, Intelligent Polymer Research Institute and ARC Centre of Excellence in Electromaterials Science, The University of Wollongong, Australia

    • Highly efficient dye-sensitized solar cells have been fabricated with Ru complex dyes adsorbed on nano-porous TiO2 electrodes (RuDSC). While the efficiency of the RuDSC has not been improved much for last decade, various dyes including metal complex and metal free organic dyes for DSC have been synthesized. In view of short-circuit current, some dyes have shown comparable values with that of RuDSC. On the other hands, open-circuit voltage (Voc) is always lower than that of RuDSC. It has been reported that lower value of Voc in the case of metal free organic dyes was attributed to the shorter electron lifetime, which corresponds to the transfer rates to dye cations and I3-. DSC prepared with porphyrin dyes have shown relatively high efficiency among metal complex dyes, but have the same problem with organic dyes, that is lower values of Voc. In order to study the causes of the low Voc, we measured the electron lifetime and diffusion coefficient (D) in DSCs prepared from porphyrin dyes, and found that shorter lifetime and faster D. We then compared the results with those in DSCs with organic dyes and Ru complex dyes under different electrolyte compositions. We also measured transient absorption of cationic state of these dyes. The electron transfer rates to dye cation and I3- are discussed in view of the structure of these dyes.