Synthesis of Cu2ZnSnSe4 from nitrate and selenite inks for use as an absorbent layer in the design of solar cells

Abstract

This research was conducted to identify two acceptable precursors and methods of synthesis for the manufacture of photovoltaic cells. The kesterite Cu2ZnSnSe4, a promising material for solar cell applications, was synthesized from metal salts of Cu, Zn, Sn, and Se, by two low-cost routes: the direct dissolution of metal nitrates, and coprecipitation of selenites. In both cases, inks were obtained and deposited as thin-films by the Doctor Blade technique on glass substrates coated with molybdenum. The films were annealed in an oven at 550 °C by 30 minutes. The phases of each thin film were analyzed by X-ray diffraction and Raman scattering. The morphology and the thickness of the layers were observed using a scanning electron microscope. The optical band gap was determined by ultraviolet-visible spectroscopy and the Tauc equation. The results confirmed the main phase of kesterite material, consistent with a tetragonal crystalline system oriented along the plane (112). These values are consistent with those found by Raman spectroscopy, where the main vibrational mode was identified at 173 cm−1 and 196 cm−1, characteristic of mode A vibration, and 243 cm−1 of mode B vibration; typical of kesterite. Simultaneously, a band gap of 0.89 eV was identified. These results demonstrate the effectiveness of the selenite’s coprecipitation method for synthesis of kesterite, without evidence of secondary phases. This determines the possibility of using this material in solar cell applications.