Annealing Effect on Cu2ZnSnS4 Thin Films Deposited by Chemical Bath Method for Solar Cell Application

I-2-II-IV-VI4 compound semiconductors are important solar cell materials with optical and electrical properties that can be tuned for optimum device performance. Recently, there has been an effort to investigate direct band gap Cu2ZnSnS4 material which could be used as a solar cell absorber material because of its low-cost and non-toxicity. In the present paper, CZTS absorber thin films have been successfully synthesized onto glass substrate by Chemical Bath Deposition method. These as-grown CZTS films have been further subjected to thermal annealing for controlling morphology and grain size of the absorber layer in solar cell. The as-grown and annealed films have been characterized by X-ray diffraction (XRD), optical absorption, scanning electron microscope (SEM) for structural, optical and surface morphological properties, respectively. XRD analysis revealed that structure of CZTS film is polycrystalline in nature with tetragonal structure after annealing. The SEM exhibits grain growth as a function of annealing treatments corresponding for modifications in the grain size. The band gap of annealed CZTS films has found 1.51 eV which are calculated by absorption spectroscopy and band gap value is nearly equal to theoretical value of solar energy spectrum.