Thermal stability of the C106 dye in robust electrolytes.

Thermal stability of the C106 dye in robust electrolytes.
We have investigated the thermal stability and degradation chemistry of the ruthenium dye C106 (Figure 1) at 80 ◦C in the “robust” electrolyte “B” comprised of 1.0 M DMII, 0.03 M I2, 0.5 M NBB, and 0.1 M GuNCS in 3-methoxypropionitrile (3-MPN) introduced by Gao et al. in 2008. [1].
Figure 1 Thermal degradation of C106 bound to TiO2 at 80 ºC in dark as a function of heating time.
● C106 = RuLL´(NCS)2 ■ RuLL´(NCS)(NBB)+ ▲ RuLL´(NCS)(3-MPN)+
The C106 dye was attached to the surface of TiO2 nano-particles and stable colloidal solutions of the particles were prepared in electrolyte mixture B. The solutions were thermally treated at 80 ◦C for 0-2000 hours followed by dye extraction and analysis by HPLC coupled to UV/Vis and electro spray mass spectrometry [2]. Figure 1 shows the concentration profiles of C106 samples prepared under ambient and glove box conditions as a function of the heating time. Preparation of the samples under strict atmospheric moisture control in a glove box gives the best results with a steady state surface concentration of 80% intact C106 and 20% NBB substitution product after ~1500 hours of heating at 80 ºC. If dye degradation was the only loss mechanism in a DSC during thermal treatment the reduction in the DSC efficiency after long term thermal treatment may be estimated to 12%[3]. The dye stability therefore does not seem to be the limiting factor in full filling the requirements of the IEC 1215 standard thermal stress tests.