Besides the effect on the HOMO and LUMO energy levels, the acidity affects the Ipc and Ipa of the dyes. As can be seen in Table 2, the ratio n of the cathodic to the anodic peak currents of the N719 and the as-extracted PL dye had almost matching values of 0.62 and 0.65, respectively. This indicates that the redox reaction in both dyes was irreversible. As expected, the PL dyes with high acidity exhibited significantly increased Ipc and therefore PL dyes with low pH (up to pH 4) had a high ratio n, which decreased for stronger acidity. Consequently, up to pH 4, the effect of acidity on the dye was to improve Ered and enhance its reversibility. Ipc/Ipa > 2 also shows that the electrons in the dye (EHOMO) were more easily regenerated by the electrolytes.