Solar cells based on CIGS are on the path of industrialization, and First Solar is now the world’s first solar module manufacturer with its CdTe technology. However there are doubts about the availability of indium in the long-term, and there are difficulties related to the handling of cadmium. It is therefore necessary to start working on the replacement of these technologies in the medium term. A possible solution is to replace the indium in chalcopyrite by a pair consisting of a zinc atom and a tin atom. This material, noted CZTS for Copper Zinc Tin Sulfur is promising and has already shown efficiencies of around 10%. This project aims at developping a French working group on CZTS, working both on understanding the crystal chemistry and the band structure of the material, and the development of processes. It will therefore be possible to make a technology in the medium term to French companies that could develop the technology commercially. In order to accelerate the developement of this technology, fundamental and applied research will be led : - ab initio simulations and chemical crystallography studies will be led in order to to improve understanding of the CZTS material CZTS - three processes of CZTS deposition will be investigated : o Vacuum deposition has the greatest potential in terms of efficiency o Two chemical techniques, electrodeposition and sol-gel, are mastered by the partners, both academic and industrial.