Effect of annealing atmosphere and temperature on the properties of the sol-gel spin coated Cu2ZnSnS4 (CZTS) thin films

Abstract

Cu₂ZnSnS₄ (CZTS) is emerging as a promising material for thin film solar cell applications.  The reason behind its popularity is the requirement of low-cost and easily available materials, low band gap (1.4-1.6 eV) and high absorption coefficient of CZTS. In the present study, CZTS thin films are prepared using a low cost sol-gel spin coating method. Thin films of CZTS are generally annealed under the H₂S + N₂ atmosphere. The handling of H₂S is its self a challenge and it is not an environment friendly route. Hence, to move towards the environment friendly preparation of CZTS thin film, the thin films are annealed under open air, vacuum and argon atmosphere. The effect of annealing atmosphere on the optical, structural and morphological properties of CZTS thin films is observed. Further, to optimize the properties of CZTS thin films, the annealing temperature is also varied from 400-600ºC. In addition, the solar cell is fabricated using the optimum condition. More than 3 % of power conversion efficiency is achieved by solar cell. For film characterization X- ray diffraction, scanning electron microscope are used for structural and morphological analysis, respectively. The optical properties are studied using. The solar cell performance is measured using Keithley 2400 solar simulator.