Fabrication of CZTS and ZnO nano-rods for solar cell application

Abstract

Transparent zinc oxide (ZnO) films had been grown on indium tin oxide (ITO) glass using potentiostatic cathodic deposition technique. Aqueous zinc nitrate was used as electrolyte. In this project, different deposition parameters such as applied cathodic potential, and concentration of electrolyte had been used to fabricate the ZnO films. Their structural and optical properties were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), diffuse reflectance UV-VIS spectrophotometer and photoluminescence (PL) spectrometer. The band gap of the ZnO was determined using the emission curve of photoluminescence which is about 3.3eV. On the basis of our measurements, the effects of different deposition parameters on the structural and optical properties of the ZnO films have been investigated.Cu2ZnSnS4 (CZTS) nanoparticles with sizes of 515 nm were successfully synthesized using hydrothermal process at a relatively low temperature of 130oC. Non-toxic and inexpensive precursors including copper chloride, zinc chloride, thiourea and oleyamine were used. The effects of the key processing parameters, such as hydrothermal temperature and composition ratio of the precursors, on the structural properties of CZTS were investigated. The higher the reaction temperature within the range between 130oC and 180oC the better the crystallinity of CZTS was. In order to obtain stoichiometric CZTS, the amount of Zn and S used were far more than they supposed to be used i.e. Cu:Zn:Sn:S=2:5:1:9. CZTS nanoparticles were then dispersed into toluene to form suspending solution which was deposited on ITO-coated glass substrates using dip-coating method. The structural properties of CZTS particle films were characterized with X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Transmission Electron Microscopy (TEM) and Raman spectroscopy. The band gap of the CZTS was determined using the emission curve of photoluminescence.Based on the ZnO films and CZTS nanoparticles, solar structures were developed. Different kinds of solution were used to disperse the CZTS nanoparticles on top of ZnO/ITO films. After successfully dispersion of the CZTS, Molybdenum was used as the top electrode. Finally, the result of this photovoltaic device was measured by solar stimulator.