Stability of dye-sensitized solar cells under extended thermal stressElectronic supplementary information (ESI) available: The UV-vis spectra and chemical structures of Z907 and Ru505 dyes (Fig. S1), electrical parameter trend under 85 °C thermal stress (Fig. S2), Nyquist spectra of Z907/L-12 samples at −0.62 V (Fig. S3), plot of recombination resistances versus equivalent conduction band for Z907 samples (Fig. S4), and IS analysis for Ru-505 based devices (Fig. S5). See DOI: 10.1039/c7cp04598k

In the last few decades, dye-sensitized solar cell (DSC) technology has been demonstrated to be a promising candidate for low cost energy production due to cost-effective materials and fabrication processes. Arguably, DSC stability is the biggest challenge for making this technology appealing for industrial exploitation. This work provides further insight into the stability of DSCs by considering specific dye-electrolyte systems characterized by Raman and impedance spectroscopy analysis. In particular, two ruthenium-based dyes, Z907 and Ru505, and two commercially available electrolytes, namely, the high stability electrolyte (HSE) and solvent-free Livion 12 (L-12), were tested. After 4700 h of thermal stress at 85 °C, the least stable device composed of Z907/HSE showed an efficiency degradation rate of ∼14%/1000 h, while the Ru505/L-12 system retained 96% of its initial efficiency by losing ∼1% each 1000 h. The present results show a viable route to stabilize the DSC technology under prolonged annealing conditions complying with the IEC standard requirements. The graphical abstract shows 5 equivalent DSCs in masterplate configuration and their performance stability under thermal stress @85 °C during 4700 h. Ru505/L12 cells resulted the most stable dye/electrolite pair by retain more than 95% of initial efficiency.