Stability of ruthenium/organic dye co-sensitized solar cells: a joint experimental and computational investigation

We carried out a joint experimental and theoretical study of the stability of dye-sensitized solar cells using a mixture of black dye (N749) and a Y1 organic co-adsorbent. The aim of this work was to investigate the stability of these highly efficient sensitizers. The co-sensitized device showed remarkable stability under the conditions investigated (1100 h of about 1 Sun light soaking at 55 °C). The partial desorption of the organic co-adsorbent was identified as a possible cause of the slight reduction in the photocurrent value. Theoretical investigations on the dye-sensitized semiconductor surface using DFT methods showed a considerably lower adsorption energy for Y1 compared with N749, in particular upon oxidation, possibly leading to desorption of the dye under working conditions. The devices using only the Y1 organic dye consistently showed a considerably lower stability.