Fabrication of Cu2ZnSnS4 films by sulfurization of Cu/ZnSn/Cu precursor layers in sulfur atmosphere for solar cells

Cu2ZnSnS4 (CZTS) absorbers were grown by sulfurization of Cu/ZnSn/Cu precursors in sulfur atmosphere. The reaction mechanism of CZTS formation from the precursor was analyzed using XRD and Raman spectroscopy. The films with a single phase CZTS were formed at 560 and 580 °C by sulfurization for 30 min. The film grown at 560 °C showed bi-layer morphology with grooved large grains on the top and dense small grains near the bottom of the film. On the other hand, the film grown at 580 °C showed large grains with grooves that are extended from surface top to bottom of the film. The solar cell fabricated with the CZTS film grown at 560 °C showed the best conversion efficiency of 4.59% for 0.44 cm2 with Voc=0.545 V, Jsc=15.44 mA/cm2, and FF=54.6. We found that further improvement of the microstructure of CZTS films can increase the efficiency of CZTS solar cells.

XRD patterns of CZTS samples taken during temperature ramping and illuminated current–voltage characteristics of CZTS thin film solar cells.Figure optionsDownload as PowerPoint slideHighlights
► Formation of CZTS thin films by sufurization of Cu/ZnSn/Sn precursors layers in sulfur ambient.
► Growth of CZTS film rapid due to the presence of quasi-liquid Cu2−xS phase during temperature ramping.
► 4.59% efficient CZTS thin film solar cell achieved with CZTS absorber grown at 560 °C for 30 min.