Optimization of sulfurization time for properties of Cu2ZnSnS4 films and cells by sputtering method

Abstract

Cu2ZnSnS4 (CZTS) thin films have been fabricated by sputtering ZnS/Sn/CuS and following the sulfurization process. In order to study the optimal sulfurization process, the effects of sulfurization time on the quality of CZTS thin films and solar cells are investigated. The sulfurization process was carried out at 580 °C for 10, 20, 30, 40 and 50 min respectively with a ramp rate of 45 °C min−1 in details. The results show that sulfurization time of 30 min provides a favorable sulfurization environment to form kesterite CZTS thin films owing to the highest crystallinity, dense and smooth surface morphology with larger grains and the best optical–electrical properties. Finally, the CZTS solar cells are fabricated with the structure of SLG/Mo/CZTS/CdS/i-ZnO/ITO/Al, and the best power conversion efficiency of 5.41% was obtained with an open-circuit voltage of 599 mV, a short-circuit current density of 18.71 mA cm−2 and a fill factor of 44% under the annealing time for 30 min.