1. Impedance Characterization for Dye-Sensitized Solar Cells Sonia Ruiz Raga Photovoltaic and Optoelectronic Devices Group Universitat Jaume I – Castelló – Spain http://www.elp.uji.es/

2. Introduction: Emergent DSC technology… … but first we have to go to the lab…

3. Introduction: Preparation of a standard Grätzel cell(1) Charachterization and modelling(2) (1) Wang, Q.; Ito, S.; Grätzel, M.; Fabregat-Santiago, F.; Mora-Sero´,I.; Bisquert, J.; Bossho, T.; Imai, H. J. Phys. Chem. B 2006, 110, 25210. (2) Chapter “Impedance spectroscopy: A general introduction and application to dye-sensitized solar cells” By J. Bisquert i F. Fabregat-Santiago in “Dye sensitized solar cells” Edited by K. Kalyanasudaram, EPFL press, Laussane, Switzerland (2010) ISBN: 978-2-940222-36-0 Distribution: CRC Press, Boca Raton, FL, USA (2010) ISBN: 948-1-4398-0866-5

4. Preparation of a Grätzel cell: Ingredients: Ruthenium-based Dye FTO glass Surlyn (thermoplastic polymer) Ti-isopropoxidesolution Chloroplatinic acid Nanoparticle TiO2 paste I- / I 3- electrolyte

5. Preparation of a Grätzel cell: 1- Clean the TCO glass 3- Deposite the working electrode of nanoporous TiO2 paste 450º 2- Deposite a compact layer of TiO2 by spray pirolisis TiO2-isopropoxide solution

6. Preparation of a Grätzel cell: 4- Calcinate at 450º during 30 min 5- Dip in dye solution overnight 6- Prepare the Pt counter - electrode Chloroplatinic acid 450ºC

7. Preparation of a Grätzel cell: 7- Seal the device 8- Fill with electrolyte Surlyn (thermoplastic polymer) 9- Weld Sn contacts

8. Device completed! Nanoporous TiO2 layer Glass substrat Adsorbed DYE FTO layer I- / I3- electrolyte Compact TiO2 layer Pt counter electrode

9. Characterization and modelling:

10. J – V curve: The generation gives the photocurrent Open-circuit voltage is determined by energetic of the materials and recombination The fill factor gives the reduction of the power with respect to:

11. Impedance Spectroscopy: Solution Solid High frequency Low frequency

12. Impedance Spectroscopy:

13. Impedance Spectroscopy: Rs Rco Rct Rt RPt Cco Cµ Zd Rbl CPt Cbl

14. Characterization and modelling: Rs Rco Rct Rt RPt Cco Cµ Zd Rbl CPt Cbl

16. Counter electrode resistance & capacitance

18. Counter electrode resistance & capacitance

21. Counter electrode resistance & capacitance

22. Recombination resistance & capacitance of TiO2

24. Future projects: Solid state solar cells Bulk heterojunction solar cells Other semiconductor electrodes Etc…

25. Acknowledgements: Chapter “Impedance spectroscopy: A general introduction and application to dye-sensitized solar cells” By J. Bisquert i F. Fabregat-Santiago in “Dye sensitized solar cells” Edited by K. Kalyanasudaram, EPFL press, Laussane, Switzerland (2010) ISBN: 978-2-940222-36-0 Distribution: CRC Press, Boca Raton, FL, USA (2010) ISBN: 948-1-4398-0866-5