**2.3 Challenges to take up**

Advances in the field have enabled CIGSe based technology to exceed the 20% yield recorded in 2010 and yields close to 23% in 2016. If this technology is actually offering very good yields for thin films structures, it is also facing many economic, environmental and competitive challenges strongly linked to this last decade requirements.

#### • **The first challenge: Reducing production costs**.

The European Union has classified Indium as a critical material since 2010 due to the drastic lowering of its reserves following its multi-field use where demand is increasingly growing in addition to the photovoltaic market (ITO screen, LED, etc.) and the instability of its cost is already hindering the development of CIGSe technology. Among the distinct avenues of research aiming at reducing the use of Indium, the reduction of the thickness of the CIGSe layer is the subject of this work.
