Green Atmospheric Aqueous Solution Deposition for High Performance Cu2ZnSn(S,Se)4 Thin Film Solar Cells

Abstract

Environment‐friendly process, low production cost, and simple operation are regarded as key factors for scalable kesterite photovoltaic applications. Herein a green ammonium thioglycolate (TGAm)‐based aqueous solution route has been developed to deposit Cu2ZnSnS4 films. It is found that sinstering in ambient air is as good as in argon, making the production process more affordable and reproducible. TGAm is more active than other alkylthiols with longer alkyl chains and has a strong coordination capability toward metal ions, which is a key factor in the dissolution of a series of metal oxides. Meanwhile, TGAm is widely used in biopharmaceuticals and hairspray, demonstrating good biological compatibility. Moreover, a low level of Ag doping can be successfully incorporated into the host lattice of the CZTSSe to form a homogeneous (Cu1−x,Agx)2ZnSn(S,Se)4 (CAZTSSe) alloy material by this aqueous process. Benefiting from the effect of Ag doping, the initial power conversion efficiency is successfully enhanced from 5.86% (x = 0) to 7.38% (x = 2%).