Study of heterostructures of Cu₃BiS₃-buffer layer measured by Kelvin probe force microscopy measurements (KPFM)¹

The interface formed between Cu₃BiS₃ thin films and the buffer layer is a potentially limiting factor to the performance of solar cells based on Al/Cu₃BiS₃/buffer heterojunctions. The buffer layers of ZnS and In₂S₃ were grown by co-evaporation, and tested as an alternative to the traditional CdS deposited by chemical bath deposition. From the Kelvin probe force microscopy measurements, we found the values of the work function of ZnS, In₂S₃, and CdS, layers deposited into Cu₃BiS₃. Additionally, different electronic activity was found for different grain boundaries (GBs), from studies under illumination, we also found the net doping concentration and the density of charged GB states for Cu₃BiS₃ and Cu ₃BiS₃/CdS.