Photocurrent oscillations in natural dyes-based DSSCs with different mordant and assistants: Their role in oscillations and color stability

Cochineal was used as natural dye together with alum and tin as mordant and five assistants (also called brighteners): citric acid, acetic acid, oxalic acid, sodium metasilicate, and cream of tartar. The mordant improves the adhesion between the dye and the mesoporous, stabilizing and intensifying the color giving it firmness and fastness, with an increment in the lifetime. The cells, prepared using mordant and assistants, were illuminated with an abrupt transition dark-to-light; under these conditions, unstable oscillations appeared on top of the output current. These oscillations were produced because the cell was shifted far from equilibrium by the fast illumination; the dependence of the oscillations with the concentration of mordant and assistants is described; additionally, the color stability was determined based on the additive's concentration and the lifetime on the irradiation time. No other cells parameters were determined in this work. [Display omitted] •Output photocurrent controlled by mordant and assistants in DSSC.•Color stability using different mordant and assistants.•A thermodynamic model for the non-linear oscillation.•Relation between the output photocurrent and the double layer formation.•Performance of DSSC using cochineal and alum.