Performance enhancement through post-treatments of CdS-sensitized solar cells fabricated by spray pyrolysis deposition

The CdS-sensitized solar cells (CdS-SSC) were fabricated by spray pyrolysis deposition (SPD) method. The performance of the cells was greatly improved through post-treatments that included thermal oxidation at 500 degrees C for 30 min in an air atmosphere and subsequent chemical etching by 40 mM aqueous HCl solution at room temperature for 30 min, as compared to as-deposited CdS-SSC. The CdS-SSC in a I-/I-3(-) electrolyte system was resulted in the improvement of J(sc) (3.3 -> 5.2 mA/cm(2)), V-oc (697 -> 758 mV), FF (41.4% -> 46.9%), and (0.95% -> 1.84%). Similarly, the efficiency of CdS-SSC in a noncorrosive polysulfide electrolyte system was also enhanced by the proposed thermal oxidation and etching process. The increase in the cell efficiency is attributed to the reduced charge recombination among sensitizer themselves through the mitigation of overaggregated CdS sensitizers deposited by SPD.