An-Najah Staff

Polycrystalline CdS/ZnS thin films were prepared by chemical bath deposition (CBD) technique on fluorine-dopedtin oxide (FTO) coated glass substrates. Enhancement of deposited CdS/ZnS thin film characteristics at solid/liquidinterface in photoelectrochemical (PEC) systems was investigated. Deposited CdS/ZnS thin films were exposed todifferent treatment methods and different experimental conditions. The films were heated to desired temperatures(300ºC, 400ºC) under air. Cooling of heated films to room temperature was achieved by either slow cooling orquenching. Etching of film surface was conducted using dilute HCl solution. The effect of such treatment on thefilm photoelectrochemical characteristics was measured by monitoring different parameters, such as: open-circuitvoltage (Voc), short-circuit current density (Jsc), dark current density-potential (J-V) plots, photo J-V plots,conversion efficiency (η), fill factor (FF), Scanning electron microscopy (SEM), X-ray diffraction, together withelectronic absorption and photoluminescence (PL) emission spectra. The characteristics of CdS/ZnS thin films inPEC systems were enhanced by controlling different experimental conditions, controlling preheating temperaturesand controlling cooling rates. The dark- and photo-current densities vs. potential plots were improved by annealing.Cell efficiency, fill factor, short-circuit current densities ( Jsc ) and SEM results were enhanced for the annealedCdS/ZnS films. The best annealing temperature for CdS/ZnS films was found to be 300ºC at which the photo J-Vplots and cell efficincy were improved significantly. Slowly cooled electrodes from temperature 300ºC, gave betterdark and photo current density vs. potential plots with higher efficiency than their quenched counterparts. SEMmeasurements were consistent with these findings, and showed better surfaces for slowly cooled CdS/ZnS thin filmelectrodes. Maximum values of conversion efficiencies were obtained by slow cooling ofpreheated CdS/ZnS electrodes cooled from temperature 300ºC compared to that of electrodes cooled from 400ºC.The effect of coating the CdS/ZnS electrodes with MnP/polysiloxane was also studied. The (Jsc) values of coatedCdS/ZnS films (with certain Zn ratios) were significantly enhanced. The MnP/polysiloxane coating introduces acharge-transfer mediator species that enhances current and electrode stability.