Improvement of Cu2ZnSnS4 thin film performance by using oxygen-containing Cu-Zn-Sn precursor

The CZTS thin film fabricated based on Cu-Zn-Sn (CZT) or Cu-Zn-Sn-S precursors have difficulties in making a pinhole-free and flat CZTS thin film. In this paper, Cu2ZnSnS4(CZTS) thin films were fabricated based on oxygen-containing Cu-Zn-Sn precursors. By intentionally introducing O into Cu-Zn-Sn precursors, sudden volume expansion from precursor to CZTS thin films can be avoided and smooth CZTS film surfaces without pinholes were produced. Oxygen-containing Cu-Zn-Sn precursors were prepared by sputtering ZnO, Cu, and Sn targets successfully. MoS2 formation could be suppressed by introducing ZnO as a barrier layer between CZTS absorber and Mo back contact interface during the sulfurizing process under high sulphur pressure. The short circuit current density (Jsc) and open circuit voltage (Voc) of CZTS solar cells could be increased by optimizing the sulfurization temperature. And the best conversion efficiency of CZTS solar cells from oxygen-containing precursors was 4.97 %, with an open circuit voltage of 566 mV, a short circuit current density of 21.44 mA/cm(-2) and a fill factor of 41 %.

Automated summary

By intentionally introducing oxygen into the Cu-Zn-Sn precursors, CZTS films with smooth surfaces and no pinholes were successfully fabricated. Additionally, the formation of MoS2 was suppressed by introducing ZnO as a barrier layer during the sulfurizing process. Optimizing the sulfurization temperature also led to an increase in short circuit current density and open circuit voltage of the CZTS solar cells, resulting in a conversion efficiency of 4.97% with improved performance.