The impact of different Ag/(Ag plus Cu) ratios on the properties of (Cu1-xAgx)2ZnSnS4 thin films

In this work, the effects of 0%, 3%, 6% and 10% Ag doped on the properties of Cu2ZnSnS4 (CZTS) thin films and solar cells are investigated by sputtering different Ag intermediate layer on Mo-coated soda lime glass substrate. The result shows that the partial substitution of Ag with Cu for (Cu1-xAgx)(2)ZTS(4) (CAZTS) thin films not only can obtain the uniform and compact grains with larger size, but also can reduce the amount of Cu-Zn anti-site and Cu vacancies (V-Cu) and decrease the thickness of MoS2 and voids at the back contact. Therefore, the CAZTS solar cells can attain a higher open circuit voltage (V-oc), short circuit density (J(sc)), fill factor (FF) and efficiency compared with pure CZTS solar cells, which may be attributed to reducing the recombination at boundary grains and the interface between Mo and absorbers as well as the series resistance (R-s) due to the high-quality grains. However, the different Ag contents of CAZTS absorbers create the different propriety of CAZTS devices. In short, the performance of CAZTS devices are enhanced markedly under the optimal Ag-incorporation content, and the power conversion efficiency is successfully increased from 3.45 (x=0) to 5.44% (x=6%).