Cu and CuS are introduced and compared in fabrication of CZTS based solar cells.
CZTS thin films fabricated by stack SnS/Cu/ZnS show better morphology.
CZTS solar cells annealed by stack SnS/CuS/ZnS with Sn powder show better performance.
3.79% efficient CZTS solar cell was obtained by CBD method with stack SnS/Cu/ZnS.