| Cu2Zn Sn S4(CZTS) is a direct bandgap semiconductor material, which has high light absorption coefficient(>104 cm-1) and suitable bandgap(about 1.50 e V) matching the solar radioation, meanwhile, its elemental compositions are earth-abundant and non-toxic. With these excellent properties, CZTS is considered as one of the most extensive application prospects absorber layer materials in the field of solar cells. Currently, researchers have focused on CZTS thin film and nanoparticles prepared by vacuum methods and non-vacuum methods with low-cost and low energy consumption. Vacuum process is so complex that its cost advantage is not obvious, but non-vacuum methods usually use expensive or toxic organic solvents. Thus, to explore low-cost and environmental friendly solvent for the preparation of CZTS materials is very imminent. The researches on crystal structure and properties of CZTS mainly focused on nanoparticles, very few on the micro-size crystal so that there is not deep understanding on the intrinsic properties of CZTS-based micron materials. Therefore, explore the process of preparation of micron CZTS single crystal particles has important role on deepen study of CZTS material and the development of CZTS-based solar cells.In this paper, we successful synthesized CZTS materials with the assistance of environmental and inexpensive solvent deionized water(H2O), and further to optimize the reaction conditions; Besides, CZTS-based micron single-crystal particles was prepared by molten salt method, we investigated the influences of experimental conditions on the structure,morphology and photoelectric properties of samples. Photoelectric properties of CZTS monocrystalline solar cell using CZTS micron particles as absorbing layer were investigated. The main work is as follows:(1)We synthesized kesterite CZTS nanoparticles by hydrothermal method and optimized the reaction process. The influences of experimental conditions(hydrothermal reaction temperature, the acidity of the precursor solution,the amounts of ethylenediaminethe and so on) on the morphology and structure of the samples were investigated. The results showed that high reaction temperature and increase p H of the precursor solution contribute to the formation of CZTS particles.We find that products, phases gradually shift from kesterite to wurtzite with the amount of ethylenediamine increased. The bandgap energy of sample was estimated to be 1.52 e V, which is suitable for application in the solar cell device.(2)We prepared kesterite CZTS micro-size single crystal particles by molten-salt growth method, optimized the reaction conditions and researched its growth mechanism. We use sulfide as raw materials, Cs Cl as flux successfully prepare CZTS micro-size particles through molten salt growth method; Besides, the influences of experimental conditions(the reaction temperature and the molar ratio of Cu/Zn/Sn in precursor and so on) on the structure and morphology of CZTS micron single crystal particles were investigated. We also discussed the crystal growth mechanism of CZTS micron particles. The results showed that when the reaction temperature between 750 oC and 800 oC, "Ostwald ripening" is main growth mechanism for the growth of spherical micron CZTS. When the reaction temperature is 850 oC, "joins growing" is dominant mechanism for the growth of the columnar crystal CZTS. Mo/CZTS single crystal grains/Cd S/i-Zn O/AZO structure flexible substrate-solar cell prepared based on the micro-particles produced 223.3m V voltage under midday sun of Zhanjiang, show that this new configuration micron monocrystalline solar cell has potential great photovoltaic properties.(3)We synthesized Cu2Zn1-x Fex Sn S4 micron single crystal particles by molten-salt growth method and researched its optical and magnetic properties. We mainly explore the optical and magnetic properties of Cu2Zn1-x Fex Sn S4 prepared under different content of Fe in precursor. The results showed that the bandgap energy of sample decreases with the molar ratio of Fe S/(Zn S+Fe S) increases. Field cooling magnetization of the corresponding samples increase with content of Fe increase. Samples appear hysteresis loop at at room temperature, however, sample showed strong magnetic under low temperature(2K) and magnetic field intensities of samples increase with content of Fe increase. |
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