CIGS is a tetrahedrally bonded semiconductor, with the chalcopyrite crystal structure, and a bandgap varying continuously with x from about 1.0 eV (for copper indium selenide) to about 1.7 eV (for copper gallium selenide).

CIGS is a tetrahedrally bonded semiconductor, with the chalcopyrite crystal structure.

Upon heating it transforms to the zincblende form and the transition temperature decreases from 1045 °C for x = 0 to 805 °C for x = 1.

[1] It is best known as the material for CIGS solar cells a thin-film technology used in the photovoltaic industry.

Improvements in efficiency have made CIGS an established technology among alternative cell materials.