SILVER-DOPED CDS FILMS FOR PV APPLICATION

CdS : Ag thin films were deposited by the chemical deposition method ( solution growth), on SnO2 thin transparent electrodes, to obtain n-typ e window layer for PV-cell. CdS thin films were doped with silver by a n ion-exchange process in a neutral 0.025 M thiosulphate Ag-complex so lution. Best results were achieved at immersion times of 20-30 s at ro om temperature. For the sake of comparison, the doping was performed o n 1/2 of the substrate surface, while the remaining part was left undo ped. SnSx thin layer was deposited on the top of such a n-type layer p repared in the same way the p-type layer was selected due to its simpl icity of preparation and the possibility for variation of the band gap (E-g), by varying x in the compound. Ohmic contact was produced by gr aphite paste backelectrodes. Two different types of PV cells were prod uced on the same test sample, SnO2/CdS : Ag-SnSx/C and SnO2/CdS-SnSx/C , in order to study the influence of the Ag doping of CdS, on the PV c ell parameters. Dark and light I-V characteristics were recorded for t he two types of cells at several different light intensities. Consider able enhancement of all cell parameters, efficiency (eta), fill factor (FF), diode factor (a), short-circuit current (I-sc), etc., was obser ved on the CdS : Ag-based sample. Spectral sensitivity in VIS-NIR part of the spectrum, recorded on the two types of cells, showed an improv ement on the CdS : Ag-based PV cell. (C) 1998 Elsevier Science B.V. Al l rights reserved.