Improving the efficiency of CdS/CdTe solar cells by varying the thiourea/CdCl₂ ratio in the CdS chemical bath

Abstract

In this work, the influence of the properties of CdS thin films grown by chemical bath deposition upon the characteristics of CdS/CdTe solar cells, when varying the thiourea concentrations in the CdS bath solution, is studied. The important solar cell parameters such as short circuit current (Jsc), open circuit voltage (Voc), fill factor (FF) and efficiency (η) were measured and it was noted that they improve for thiourea/CdCl2 ratios (in the CdS deposition solution) up to 5, and drop for higher ratios in the range investigated. In addition, the ideal diode factor (n), saturation current (Jo) and series resistence (Rs) were studied under illumination and dark conditions. The results could be related to several factors, among them, the photoconductivity properties of the layers and the change of the CdS1−xTex layer at the CdS–CdTe interface.