Crystallisation study of the Cu₂ZnSnS₄ chalcogenide material for solar applications

Abstract

Second generation thin-film chalcogenide materials, in particular CuInGa(S,Se)2 (CIGS) and CdTe, have been among the most promising and quickly became commercial candidates for large-scale PV manufacturing. These materials offer stable and efficient (above 10%) photovoltaic modules fabricated by scalable thin-film technologies and cell efficiencies above 20 % (CIGS). Indium-free kesterite-related materials such as Cu2ZnSnS4 have attracted significant research interest due to their similar properties to CIGS. In these materials, indium is replaced with earth-abundant zinc and tin metals. The quaternary semiconductor Cu2ZnSnS4(CZTS) is a relatively new photovoltaic material and is expected to be interesting for environmentally amenable solar cells, as its constituents are nontoxic and abundant in the Earth's crust. The CZTS thin films show p-type conductivity, a band gap of 1.44–1.51 eV that is ideal to achieve the highest solar-cell conversion efficiency, and relatively high optical absorption in the visible light range