In this study, the effect of sulfurization temperature on the morphology, composition and structure of Cu 2 ZnSnS 4 (CZTS) thin films grown on titanium (Ti) substrates has been investigated. Since Ti foils are flexible, they were preferred as a substrate. As a result of their flexibility, they allow large area manufacturing and roll-to-roll processes. To understand the effects of sulfurization temperature on the CZTS formation on Ti foils, CZTS films fabricated with various sulfurization temperatures were investigated with several analyses including x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy and Raman scattering. XRD measurements showed a sharp and intense peak coming from the (112) planes of the kesterite type lattice structure (KS), which is strong evidence for good crystallinity. The surface morphologies of our thin films were investigated using SEM. Electron dispersive spectroscopy was also used for the compositional analysis of the thin films. According to these analysis, it is observed that Ti foils were suitable as substrates for the growth of CZTS thin films with desired properties and the sulfurization temperature plays a crucial role for producing good quality CZTS thin films on Ti foil substrates.

Cu 2 ZnSnS 4 (CZTS) thin films were grown on Mo-coated soda lime glass (SLG) substrates by the sulfurization of DC magnetron-sputtered Zn, Sn and Cu metallic precursors under a sulfur atmosphere at 550 °C for 45 min. Understanding the composition and structure of the CZTS absorber layer is necessary to obtain efficient solar cells. With this aim, x-ray diffractometry, Raman spectroscopy, scanning electron microscopy, energy dispersive spectroscopy and x-ray photoelectron spectroscopy were used to investigate the CZTS absorber layers. CZTS absorber films were obtained and found to be Cu-poor and Zn-rich in composition, which are both qualities desired for efficient solar cells. CdS was used as a buffer layer and was grown by the chemical bath deposition technique. The optical properties of CdS films on SLG were searched for using a spectroscopic ellipsometer and the results revealed that the bandgap increases with film thickness increment. CZTS-based solar cells with different CdS buffer layer thicknesses were prepared using a SLG/Mo/CZTS/CdS/ZnO/AZO solar cell configuration. The influence of the CdS buffer layer thickness on the performance of the CZTS solar cells was investigated. Device analysis showed that electrical characteristics of solar cells strongly depend on the buffer layer's thickness. Highly pronounced changes in V OC , fill factor and J SC parameters, which are the main efficiency limiting factors, with changing buffer layer thicknesses were observed. Our experiments confirmed that decreasing the CdS thickness improved the efficiency of CZTS solar cells down to the lowest thickness limit.

Copper zinc tin sulfide (CZTS) absorber layer attracts so much attention in photovoltaic industry since it contains earth abundant, low cost and non-toxic elements contrary to other chalcogenide based solar cells. In the present work, CZTS absorber layers were prepared following a two-stage process: firstly, a stack of metal precursors (Copper (Cu)/Tin (Sn)/Zinc (Zn)/Copper (Cu)) were deposited on molybdenum (Mo) substrate by magnetron sputtering, then this stack was annealed under S atmosphere inside a tubular furnace. CZTS thin films were investigated using energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy and Raman spectroscopy. The effect of sulfurization time and the thickness of top and bottom Cu layer in precursors on the properties of CZTS thin films were investigated. The importance of Cu thickness adjacent to Sn to avoid detrimental phases was addressed. The significance of sulfurization time to restrict the Sn and Zn losses, formation of oxides such as tin dioxide and zinc oxide, and formation of molybdenum disulfide and voids between Mo/CZTS interface was also addressed. Moreover, cadmium sulfide buffer layer, which is conventionally used in CZTS solar cells, is replaced by an environmentally friendly alternative zinc oxysulfide buffer layer.