I attach 2 graphs of a standard ruthenium-based dye sensitized solar cell (same cell but test was conducted during different days: 29-april & 3-may). The frequencies set are:fi=200kHz & ff=100mHz, and the voltage was kept at open circuit voltage for the duration of the experiment.

Is there an explanation for why the spectra starts in the lower quadrant (for graph B) and ends with a tail that also in the lower quadrant for graph A.

...And also, what could be the reason for not obtaining three semicircles for a standard DSSC performance

So mainly my inquiry is based upon why the graph might be located at the bottom quadrant and why do we get a tail at the end?