Degradation chemistry of N719 and Z-907 dyes at elevated temperatures

Degradation chemistry of N719 and Z-907 dyes at elevated temperatures.

 

Torben Lund^a, Phuong Tuyet Nguyen^a and Hoang Thai Nguyen^b

^{aDepartment of Science, Systems and Models, Roskilde University, DK-4000, Denmark}

^{bDepartment of Chemistry, University of Sciences, HoChiMinh City, Vietnam}

     ^{The popular dye sensitized solar cell dyes N719 and Z-907 are in general accepted to be very stable under solar cell conditions below 45 ºC.1 The dyes, however, may undergo thiocyanate ligand substitution reactions with the DSC solvent and additive molecules at elevated temperatures (80-100 ºC).}

      ^{Recently we have established the mechanism and kinetics of these thiocyanate exchange reactions in both homogeneous solutions and colloidal mixtures with the dyes attached to TiO₂ particles.2,3 The half life’s at 85 ºC of  the N719 and Z-907 bound to TiO₂ particles in colloidal solutions of 3-methoxypropionitrile and 4-tert-butylpyridine (0.5M) were 120h and 150h respectively. These results indicate that the N719 and Z-907 dyes will not be able to survive a 1000h solar cell thermal stress test 4 at 85 ºC. Strategies to reduce the dye degradation at elevated temperatures will be presented.}

^References 

^{1) A. Hinsch, J. M. Kroon, I. Uhlendorf, J. Holzbock, A. Meyer, J. Feber, Prog. Photovolt. Res.}

^{Appl. 2001, 9, 425.}

^{2) H.T. Nguyen, H. M. Ta, and T.  Lund,  Solar Energy Materials & Solar Cells 2007, 91, 1934.}

^{3) P. T. Nguyen, R.  Degn, H. T. Nguyen, and T. Lund, ,  Solar Energy Materials & Solar Cells 2009 in press.}

^{4) 1215, I., Crystalline Silicon Terrestrial Photo Voltaic (PV) Moduls Design. Qualification and}

   ^{Type Approval. International Electrotechnical commission 1993.}