Incorporation of Rb cations into Cu2FeSnS4 thin films improves structure and morphology

Quaternary chalcogenide Cu2FeSnS4 (CFTS) thin film, a potential material for application as absorber layer in thin film solar cells (TFSCs), dye-sensitized solar cell and photocatalytic, are successfully synthesized by using a convenient blade-coating method. Alkali element Rb was incorporated into CFTS thin films in order to further improve the structure and surface morphology. X-ray diffraction, Raman spectroscopy and field emission scanning electron microscopy were used to characterize the phase purity, morphology and composition of CFTS particles and thin films. It showed that the diffusion of Rb ions is uniform in the films after sulfurization, Rb ions incorporation in CFTS thin films could improve the grain size and surface morphology. All the thin films became smooth and closely packed surface, the thickness of the incorporated films is around 1   μm.