Effect of Ag doping on opto-electrical properties of CdS thin films for solar cell applications

• Published in: Journal of alloys and compounds 2014-10, Vol.609, p.40-45
• Main Authors: Nazir, Adnan, Toma, Andrea, Shah, Nazar Abbas, Panaro, Simone, Butt, Sajid, Sagar, Rizwan ur Rehman, Raja, Waseem, Rasool, Kamran, Maqsood, Asghari
• Format: Article
• Language: English
• Subjects: Applied sciences; Cadmium; Cadmium sulfides; CdS; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Doping; Electrical resistivity; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Energy; Exact sciences and technology; Natural energy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Photovoltaic cells; Photovoltaic conversion; Physics; Resistivity; Silver; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Thin films; Transmission
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.04.144

•Polycrystalline CdS thin films are fabricated by means of Close Spaced Sublimation technique.•Ag is doped by simple ion-exchange technique in order to reduce resistivity of CdS thin films.•Remarkable reduction in resistivity without introducing many transparency losses. Cadmium sulfide (CdS) polycrystalline thin films of different thicknesses (ranging from 370nm to 750nm) were fabricated on corning glass substrates using Close Spaced Sublimation (CSS) technique. Optical and electrical investigation revealed that CdS thin films show an appreciable transparency (50–70% transmission) in visible range and a highly resistive behavior (106Ωcm). Samples were doped by silver (Ag) at different concentrations, using ion exchange technique, in order to reduce the resistivity of CdS thin films and to improve their efficiency as a window layer for solar cell application. The doping of Ag in pure CdS thin films resulted into an increase of surface roughness and a decrease both in electrical resistivity and in transparency. By optimizing annealing parameters, we were able to properly control the optical properties of the present system. In fact, the Ag doping of pure CdS films has led to a decrease of the sample resistivity by three orders of magnitude (103Ωcm) against a 20% cut in optical transmission.