Growth of Cu2S/CdS nano-layered photovoltaic junctions for solar cell applications

Layered Cu2S/CdS photovoltaic p-n junctions were fabricated via a simple and reproducible route. CdS inner layer was grown on ITO substrate using chemical bath deposition process for different times. The utilized bath consisted of cadmium sulfate and thiourea with concentrations of 0.05 M and 0.07 M, respectively. CdS layer grown for 600 min was uniform with a thickness of about 500 nm. Moreover, band gap energy of the CdS inner layers was measured as 2.40-2.44 eV depending on the thickness of the layer. Cu2S outer layer was formed over the CdS via ion exchange chemical route, in a bath consisting of copper chloride aqueous solution. EDS, XRD, and XPS were utilized to characterize the formation of cadmium sulfide, and copper sulfide phases during the fabrication steps of the p-n junctions. Nano-layered cell, each layer 200-250 nm in thickness was fabricated with an apparent band gap of 2.22 eV. SEM imaging of both inner and the outer layers confirmed the uniformity and homogeneity of the CdS and the Cu2S layers.