Comparative study of binary cadmium sulfide (CdS) and tin disulfide (SnS2) thin buffer layers

Abstract

Binary compound tin disulfide (SnS2) and cadmium sulfide (CdS) are the potential candidates used as a buffer layer for copper indium gallium selenide (CIGS) and copper zinc tin sulfide (CZTS) thin-film device. Herein, both compounds have been successfully prepared through simple hydrothermal (HD) and chemical bath deposition (CBD) techniques, respectively. The prepared samples were characterized by different available techniques like X-ray diffraction (XRD), atomic force microscopy (AFM), surface electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmittance electrons microscopy (TEM), UV–Visible spectroscopy and photoelectrochemical (PEC) analysis. The XRD analysis confirms the polycrystalline nature of the prepared thin films. AFM analysis showed that the SnS2 display better roughness (60 nm), grain size (75 nm) than CdS roughness (23 nm), grain size (41 nm) thin films. SEM and EDS studies revealed near stoichiometry behavior of elemental composition of the films. The optical absorption spectrum showed the direct bandgap of CdS 2.45 eV and 2.20 eV for SnS2 thin films. The PEC analysis revealed that the SnS2 thin films exhibit two times higher photoresponse (140 µA) as compare to CdS (80 µA) thin films. The SnS2 high photocurrent could be attributed to the small band gap and increase in grain size which can trap more incident light. Based on the results the SnS2 used as a buffer layer can be a good choice for an efficient photovoltaic device.