Electrodeposition using non-aqueous solutions at 170 °C and characterisation of CdS, CdSxSe(1−x) and CdSe compounds for use in graded band gap solar cells

CdS, CdS_xSe_(1−x) and CdSe compounds have been grown at 170 °C using electrodeposition from an electrolyte containing ethylene glycol as the solvent. The materials were grown for x=0, 0.22, 0.50, 0.76 and 1.00, and the x values quoted here are obtained from the XRF measurements. The resulting materials were characterized by optical absorption method for determination of band gap variation, and by XRD for bulk structure variation. It has been demonstrated that the band gap could be varied from 1.7 eV for x=0 (CdSe) to 2.4 eV for x=1 (CdS) by varying the parameter x. Bulk structure remains as hexagonal, but the corresponding lattice spacing gradually increases as the smaller S⁻² ions are replaced by larger Se⁻² ions. The photoresponse shown in photoelectrochemical cell demonstrates that all compounds grown are suitable for solar cell applications.