**2.2 CIGSe-based cells: evolution**

The scientific advances which have enabled the realization of very high efficiency thin film solar cells have taken place by successive technological leaps, the study of these different key stages is essential to understanding the complexity of the structure of a solar cell based on standard CIGSe and the problematic of this work.

Initially intended for the manufacture of photo-detectors, the first solar cells consisted of single crystals of CuInSe2 (CISe) evaporated on an alumina/molybdenum substrate. Interest in photovoltaic applications grew very quickly in regards to the good yields of around 9% obtained by BOEING in 1981. Since the 1980s, four main developments have made it possible to obtain current yields.
