Investigation of Cu2ZnSnS4-based thin film solar cells using abundant materials

Aiming to develop the solar cells free from both environmental contaminants and rare metals, thin film solar cells were produced by using Cu2ZnSnS4 (CZTS) as an absorber. CZTS thin films could be successfully formed by the vapor phase sulfurization of precursors prepared by the electron-beam evaporation on the soda-lime glass substrates. The atomic ratio of Cu/(Zn+Sn) was varied from nearly 0.5 to 1.2 to investigate the influence of the composition on the surface morphology and the optical properties. In order to optimize the sulfurization condition, we varied the sulfurization temperature from 510 degrees C to 550 degrees C. As the results, the value of the conversion efficiency of 4.53% was obtained for the cell of which CZTS absorber sulfurized at 520 degrees C.