Deposition and Characterization of Low-Cost Spray Pyrolyzed Cu2ZnSnS4 (CZTS) Thin-Films for Large-Area High-Efficiency Heterojunction Solar Cells

Abstract

Cu2ZnSnS4 (CZTS) thin films have been prepared on Mo coated soda-lime glass (SLG) substrates using a low-cost spray pyrolysis technique. Aqueous solutions of CuCl, ZnCl2, SnCl4 and thiourea were used as precursors. Spray deposition was carried out at substrate temperatures of 300-400C with varying precursor concentrations. Structural, morphological and compositional characterization of as-deposited and annealed CZTS films were carried out by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and x-ray photoelectron spectroscopy (XPS). Optical and electrical properties were measured by UV-Vis spectroscopy, van der Pauw, and Hall-effect measurements. Heterojunction solar cells have been fabricated by deposition of n-CdS window layer on spray deposited p-CZTS films. Details of film fabrication, processing and characterization are presented. Our results show that CZTS-based solar cells can be designed and fabricated by a low-cost spraying technique for roll-to-roll commercial production.