Structural, Optical, Surface Morphological and Electrical Properties of Cu2ZnSnS4 Thin Film Synthesized by Drop Casting Technique

Quaternary Cu2ZnSnS4 (CZTS) thin films have been receiving an excessive technological interest in the solar cell industry due to its outstanding optoelectronics properties. This study report the deposition of CZTS thin films on the soda lime glass substrate using simple and cost effective drop casting route. In this route, CZTS ink was prepared using CuCl2, SnCl2, ZnCl2,, Na2S as a precursors, and polyvinylpyrrolidone as a binder with de-ionized water as a solvent. The CZTS ink was then drop-cast onto the clean glass substrate at 110 C and sintered at 550 C for 1.30 h in sulfur vapor. Amorphous thin films of CZTS were deposited, and thermally converted to polycrystalline, semiconducting CZTS. Films were studied using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, field-emission scanning electron microscopy, energy dispersive spectrometer, and UV Vis spectroscopy. A polycrystalline CZTS thin films were obtained with a ratio of Zn/Sn =1.0, S / metal =1.07. The films had a band gap of about 1.56 eV. The films were p-type with a hall mobility of 32 cm(2)/Vs. These drop cast CZTS thin films can be applied as the absorber layers in solar cells. We expect that the method and idea presented in this work will provide a new way for the construction of highly efficient photo-absorber not only for CZTS, but also for other semiconductor materials.