Environmental assessment of vacuum and non-vacuum techniques for the fabrication of Cu2ZnSnS4 thin film photovoltaic cells

Cu2ZnSnS4 (CZTS) is one of the most promising alternatives for photovoltaic (PV) applications, since it is made from earth abundant and low toxicity materials. To assess the potential of CZTS PV cells in the future global market, it is useful to investigate the sustainability by assessing the possible environmental impacts of large-scale production. Life cycle assessment (LCA) of CZTS absorber layers fabricated by vacuum and non-vacuum deposition techniques has been studied using information from laboratory-scale processes as well as large scale estimations. Copper indium gallium diselenide (CIGS) was selected as a reference vacuum-based process. The paper compares the environmental impacts of the vacuum and non-vacuum processes by considering the three main damage categories of climate change, human health and eco-toxicity using Sima Pro software. The results show that the CZTS films fabricated with both deposition techniques exhibit a significant potential benefit over the CIGS thin films. The toxicity to human health was found to depend critically on the compounds and components selected for preparing the precursors. The energy consumption for processing the CZTS thin films via the non-vacuum deposition technique is considerably less than that required for the other techniques.