Preparation of Cu<sub>2</sub>ZnSnS<sub>4</sub> Thin Film by So-Gel Spin-Coated Deposition

Abstract

In this work Cu2ZnSnS4 (CZTS) suitable for the absorption layer in solar cells was successfully prepared by sol-gel spin-coated deposition. CZTS precursors were prepared by using solutions of copper (II) chloride, zinc (II) chloride, tin (IV) chloride, and thiourea. The CZTS with texture surface structures, resulting from 3 times of stacks through the cycles of spin-coated and synthesized (at 320 °C) processes, is found to be merged well together, and the thickness of the CZTS reaches ~ 3 μm. The kesterite crystallinity of the CZTS designated from the x-ray diffraction of (112), (200), (312), and (322) planes of CZTS were obtained. The optical-energy gap of the CZTS is about 1.5 eV. The average optical-absorption coefficient of the CZTS is ~ 2.4 x 104 cm-1, and the high absorption band of the CZTS covers most of the solar irradiation spectrum. This makes the CZTS the most potential material for solar cells. The chemical composition Cu:Zn:Sn:S = 30:14:16:40 of the CZTS is obtained at a synthesized temperature of 320 °C.