| 초록 |
Cu2ZnSnS4 (CZTS), one of the most promising quaternary absorber materials for solar cells, have been synthesized by novel route using two-step process. In the first step, the precursors were obtained by irradiating microwave at 700W for 10 min from aqueous solutions contacting copper, zinc, tin, and sulfur elements in the different Cu molar concentrations from 0.01M to 0.025M. In the second step, the precursors were sulfurized by annealing in the mixed H2S (5%) + N2 (95%) gas atmosphere at 550oC for 1 hour. The effects of Cu molar concentrations on the structural, compositional, and optical properties of CZTS nanoparticles were investigated. X-ray diffraction patterns, X-ray photoelectron spectroscopy, and transmission electron microscopy results showed that the sulfurized particles formed at Cu molar concentration of 0.02M were a single kieserite CZTS phase without any secondary phase. However, the sulfurized particles formed at Cu molar concentrations of 0.01M, 0.015M, and 0.025M were mixture of a kieserite CZTS phase as well as secondary phases including Cu2-xS, CuS, ZnS, SnS, and SnS2. Energy dispersive X-ray results showed that the presence of Cu in sulfurized nanoparticles increased with increasing Cu molar concentrations from 19.18 at% to 37 at%. However, these of Zn and Sn decreased with increasing Cu molar concentrations. UV-VIS spectroscopy results showed that the band gap energy of sulfurized particles decreased from 1.6 eV to 1.5 eV with increasing Cu molar concentrations. |
