CZTS Growth for Solar Cell Application by Electrochemical Deposition: pH Effect

Abstract

Electrochemical deposition method has been widely used due to its advantages in stoichiometry control, large area growth, easy to form nano-structures, being low coast, possible formation of homogeneous thin films. In this study, Cu 2 ZnSnS 4 (CZTS) thin films were deposited on ITO substrates by using single step electrodeposition method. CZTS absorber layers have been tried to be obtained at four different pH values of 4.70, 5.10, 5.70 and 6.23. Trisodium citrate was used as a complexing agent for co-electrodeposition. CZTS thin films were annealed for recrystallization in stoichiometric kesterite structure after deposition at 580 °C in sulfur powder and N 2 atmosphere for 60 min. The structural, morphological and optical properties of CZTS thin films have been investigated by using X-ray diffraction (XRD), optical absorption techniques, scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy measurements. Diffraction peaks observed at 28.53°, 37.02°, 47.33°, 56.17°, 69.23° and 76.44° correspond to diffraction of (112), (202), (220), (312), (008) and (332) planes of CZTS films deposited in solution with pH 5.7, respectively. Thin films grown at other pH values, there are peaks observed from the secondary phases. CZTS films grown at pH: 5.7 has shown three Raman modes with a strong peak at 326 cm−1 and two weak peaks at 284 cm−1 and 367 cm−1, which are not visible in other films. These peaks are due to the kesterite CZTS structure present in CZTS films and well compatible with CZTS Raman peaks.