Novel chemical route for chemical bath deposition of Cu2ZnSnS4 (CZTS) thin films with stacked precursor thin films

•CZTS films were fabricated by using stacked CBD layers.•The pH adjustment was crucial to avoid peeling-off of films.•The CBD films after post-sulfurization showed pure CZTS phase.•Band gaps of CZTS films were 1.48–1.51 eV.

A new chemical route for chemical bath deposition was proposed for deposition of Cu2ZnSnS4 (CZTS) thin films. Two stacking sequences SLG/SnS/CuS/ZnS and SLG/ZnS/CuS/SnS were demonstrated for chemical bath deposition of CZTS film. We found that peeling-off during stacking films can be solved by adjusting pH value of solution. The CBD CZTS films were followed by subsequent sulfurization to improve crystal quality. The post-sulfurized films showed kesterite crystal structure with large crystalline grains, which was confirmed by Raman spectroscopy and X-ray diffraction. The band gap energies of CZTS films were estimated to be 1.48–1.51 eV, which are promising for solar cell application.