Silver-doped CdS films for PV application

Abstract

CdS : Ag thin films were deposited by the chemical deposition method (solution growth), on SnO 2 thin transparent electrodes, to obtain n-type window layer for PV-cell. CdS thin films were doped with silver by an ion-exchange process in a neutral 0.025 M thiosulphate Ag-complex solution. Best results were achieved at immersion times of 20–30 s at room temperature. For the sake of comparison, the doping was performed on 1 2 of the substrate surface, while the remaining part was left undoped. SnS x thin layer was deposited on the top of such a n-type layer prepared in the same way the p-type layer was selected due to its simplicity of preparation and the possibility for variation of the band gap ( E g), by varying x in the compound. Ohmic contact was produced by graphite paste backelectrodes. Two different types of PV cells were produced on the same test sample, SnO 2/CdS : Ag–SnS x /C and SnO 2/CdS–SnS x /C, in order to study the influence of the Ag doping of CdS, on the PV cell parameters. Dark and light I–V characteristics were recorded for the two types of cells at several different light intensities. Considerable enhancement of all cell parameters, efficiency ( η), fill factor (FF), diode factor ( a), short-circuit current ( I sc), etc., was observed on the CdS : Ag-based sample. Spectral sensitivity in VIS-NIR part of the spectrum, recorded on the two types of cells, showed an improvement on the CdS : Ag-based PV cell.