So far we have only discussed silicon based solar cells. We will now turn our attention to PV technologies that use alternative materials. In this section we discuss the thin film chalcogenide solar cells. The term chalcogenide refers to all compounds that contain a group VI chalcogenide anion. We will first discuss the copper-indium-gallium-diselenide, or CIGS, solar cells. In this video you will learn about the material properties of CIGS.