Cu2ZnSnS4−xSex solar cells fabricated with precursor stacked layer ZnS/Cu/SnS by a CBD method

•Stacked layer by a CBD method was introduced to fabricate CZTSSe/CZTS solar cells.•3.0% and 2.2% efficiency of CZTSSe/CZTS solar cells were obtained.•The order of ZnS/Cu/SnS/Mo was demonstrably proper for a CBD-annealing route method.•ARR was introduced to deposit Cu thin film during the deposition of stacked layer.

A novel idea that using chemical bath deposition-annealing route for preparing absorber films of the Cu2ZnSnS4−xSex solar cells with stacked layers (ZnS/Cu/SnS) was proposed and carried out in this study. The absorber layers fabricated by this new method were demonstrably proper for solar cell devices. The solar cells based on the as-synthesized Cu2ZnSnS4−xSex/Cu2ZnSnS4 layers showed high photoelectric transformation efficiency, nearly 3.0% and 2.2% with the large area 1.27 cm2 and 1.80 cm2, respectively. The new method introduced here based on chemical bath deposition without the complexity of vacuum equipment may provide an alternative approach to produce large area solar cells for practical application. In addition, during the deposition of the stacked layers, a new concept called Assistant Reduction Reaction was firstly carried out to deposit metallic Cu thin film on the SnS film, which acted as not only a substrate, but also an assistant reductive agent. If the present technique is properly extended, it is possible for the preparation of other metal thin films for practical application.