Dye sensitization of antimony-doped CdS photoelectrochemical solar cell

Sb-doped CdS single crystal was used as a photoanode to fabricate a photoelectrochemical solar (PECS) cell. The three organic dyes; eosin, thymol blue and rhodamin 6G were used as sensitizers in (PECS) cell. In the absence of the dye, the results showed that with Sb-doped CdS single crystal electrode, a higher power conversion efficiency ∼9.27% has been achieved compared to ∼5.7–7.4% for pure crystal. Application of the dye in PECS cell increases the efficiency to about 13%. The efficiency reaches its maximum value when the dye concentration is (2.5×10−5)M, sufficient to cover the surface of the semiconductor electrode with a continuous monolayer of the dye. Exceeding this value resulted in a gradual decrease of the efficiency from its maximum value. Mott–Schottky plots gave a doping density of 3.14×1017 cm−3 and a space charge width of ∼4.95×10−6 cm for the sample used. A flat-band potential equal to −0.84 V, independent of both frequency and pH, was also predicted. Cyclic voltammetry (c.v.) measurements showed an anodic current peak at 0.4 V vs. SCE. The disappearance of this peak after excess addition of the reducing agent Na2S, indicates that this peak is due to the PEC corrosion of the semiconductor electrode.