CIGS solar cells: How they work

CIGS solar cells are based on the semiconductor compound Cu(In,Ga)Se2 (usually abbreviated as CIGS or CIS), which absorbs light extremely efficiently by freeing electrons. In addition to this absorber layer, these solar cells comprise an n-type semiconductor (typically CdS, ZnS, or In2S3) to form a p-n junction and to generate a voltage, and contacts to efficiently transport the electrons (typically Mo as back contact, ZnO as transparent front contact). Since these layers are not self-supporting, a substrate is required. The standard approach is to use glass as substrate. The FLISOM approach is to use plastic foils, which enables the use of low-cost roll-to-roll manufacturing technology.

Scanning electron microscope image of a CIGS solar cell (cross-section)

More information on CIGS solar cells is available at the EMPA Thin-Film Physics Group homepage.