Synthesis and characterization of CdS window layers for PbS thin film solar cells

Window layers, cadmium sulfide (CdS) thin films were synthesized on tin doped indium oxide coated glass substrates (ITO) with two different temperatures of 85 degrees C and 90 degrees C and ammonium hydroxide concentration of 1 M and 9.96 M, respectively via the chemical bath deposition (CBD) method, while absorption layers, lead sulfide (PbS) thin film were deposited on ITO substrates at room temperature using the successive ionic layer absorption and reaction (SILAR) technique. Then, these layers were integrated in ITO/CdS/PbS/Ag solar cell structures. The structural, morphological and optical properties of the thin films as well as electrical properties of the solar cells were investigated. X-ray diffraction studies showed that the CdS thin films have hezagonal structure while PbS thin films have cubic structure. The photovoltaic performance of the solar cells showed that the solar cell fabricated with CdS film deposited at 90 degrees C exhibited higher efficiency (eta) of 4.85% including J(sc) = 12.44 mA cm(-2) , V-oc = 1 V, FF = 0.39 than the CdS film deposited at 85 degrees C (eta = 3.59%, J(sc) = 9.43 mA cm(-2) , V-oc = 1 V, FF = 0.38. These results reveal that the crystal structure, surface morphology and optical properties of CdS thin film have a significiant effect on device performance and the solar cell fabricated using CdS film deposited at 90 degrees C shows better photovoltaic performance.