Fabrication Of Cu₂ZnsnX₄（X=S, Se）Thin Films From Nanoparticles And Investigation On Its Reaction Mechanism

With the looming exhaustion of fossil energy, the development and utilization of solar energy has attached more and more attention. Solar cells can directly convert solar energy into electric power via photovoltaic effect, which can be a possible power source for us. Copper Indium Selenium and Copper Zinc Tin Sulfur based thin film solar cells are attractive and promising, due to high conversion efficiency, low cost and high stability. As solar light was mainly absorbed by absorb layer in thin film solar cells, the quality of absorb layer has a great effect on the performance of solar cells. Many methods have been used in the synthesis of absorb layers, in this paper, we prepared absorb layers using metal-oxide nano-particles. The paper mainly includes two parts:In the first part, Copper Indium Sulfur (CIS) and Copper Indium Selenium (CISe) films were synthesized from monodispersed CuO and In2O3nano-particle inks. XRD and Raman spectrums have been used to analyze the crystallinity, phase composition of these films, and the morphology of films were shown in SEM pictures. The analyze results show that there are great differences in selenization and sulfuration. The sulfuration of oxide precursor can happen in a quasi-closed quartz container easily, but more time was needed in the selenization of oxide precursors. At last, possible reactions in selenization and sulfuration processes were discussed combining thermodynamic calculation using software HSC Chemistry.In the second part, Copper Zinc Tin Sulfur (CZTS) and Copper Zinc Tin Selenium (CZTSe) films were also synthesized from nano-particle inks. The Sn-loss problem of Copper Zinc Tin Sulfur in high temperature was solved by adding Sn powders when sulfurating. Qualified CZTS films with adjustable element ratios were fabricated in this way. In order to remove the stable ZnO and SnO2phase in the films, CZTSe films were made through selenization in Ar flow. Various methods have been employed to analyze the morphology, crystallinity and band gap of these films. For the detection of possible secondary phases, Raman spectrum with different laser sources was adopted and resonant Raman scattering was used to characterize ZnS phase.