Thin film solar cells based on Ag-substituted CuSbS2 absorber

CuSbS2 has been considered as a promising photovoltaic absorber material, due to its earth abundant and environmentally friendly constituents. However, the electron affinity and similar radius of cations bring heavy atomic disorders in CuSbS2 film, limiting its photovoltaic performance. Herein, we report an efficient way to reduce disorders by introducing Ag atom into CuSbS2 crystal structure. The crystal structure and chemical analysis confirm that Ag occupies the Cu position in the as-prepared films by the spray pyrolysis. The absorption spectra combined with photoluminescence measurement indicate that Ag-substituted CuSbS2 films have fewer recombination centers. The density functional theory calculation result reveals that Ag-substituted CuSbS2 has a more stable crystal structure, and the formation energy of the primary point defects obviously increases. Therefore, Ag-substituted CuSbS2 photovoltaic device shows asignificantly improved power conversion efficiency from 0.73% to 2.48%.