Facile Synthesis and Structural, Linear and Nonlinear Optical Investigation of p-type Cu2ZnGeS4 Thin Films as a Potential Absorber Layer for Solar Cells

Abstract

The fabrication of new kesterite absorber layers has drawn tremendous attention among a number of researchers. This article reports the preparation of good-quality copper zinc germanium sulfide Cu2ZnGeS4 (CZGS4) thin films via a convenient spray pyrolysis method. The fabrication of an Al/n-Si/Cu2ZnGeS4/Au heterojunction is also presented. X-ray diffraction results confirmed the tetragonal structure in the CZGS4 samples. Additionally, energy-dispersive x-ray examination illustrated that the Cu2ZnGeS4 samples possess a nearly stoichiometric composition. From the transmittance and reflectance data, the energy gap (Eg), refractive index (n) and absorption coefficient ( $$\alpha$$ ) were assessed. According to the Tauc relation, the Cu2ZnGeS4 thin samples exhibit a direct optical transition. The energy gap values were found to be in the range of 1.52–1.27 eV. The dispersion and nonlinear optical parameters of the Cu2ZnGeS4 samples were also investigated. Electrical studies showed that the Al/n-Si/Cu2ZnGeS4/Au heterojunction has good rectifying properties, with efficiency of 3.3%.