Synthesis And Characterization For The Solar Cell Absorber Layer And Transition Metal Borides

Fossil fuels on earth are reducing daily. The consumption of fossil fuels caused great pollution the natural environment by human, so finding a renewable, non-polluting energy sources becomes an urgent task. Among renewable energy sources, solar energy is a very promising green energy, which is expected to become an important source of energy for the future. The constituent elements of Cu₂ZnSnS₄（CZTS） photovoltaic material are green non-toxic, great content in the crust. The band gap of CZTS is about 1.4 eV, so it can absorb almost all of the visible light. The absorption coefficient of the material in the visible region can reach 104 cm-1, which is a very promising solar cell absorber material.During the preparation for CZTS, sulfur and tin are easily volatile at a high temperature. High temperature synthesis could easily lead to deviation from the sample ideal composition to produce hybrid phase. During the preparation CZTS material at a lower temperature, the, synthetic materials with intrinsic defects, low density, small grain size, is not conducive to the movement of the carrier, while increasing the light-generated electron or hole recombination probability, resulting in degradation of the photoelectric conversion efficiency of solar cells. To prepare a good density and large grain size CZTS single phase, we used milling and high pressure technology to synthesize high quality CZTS material.In this paper, Zn S, Sn S₂ and Cu₂ S as raw material, CZTS material was obtained by mechanical milling. Next, we used high pressure technology for high-pressure synthesis at a pressure of 5 GPa and temperature of 800 oC condition, to get close to stoichiometric CZTS solar cell absorber layer material. The sample is P-type semiconductor, and its carrier concentration is 100 times higher than the reported data. So it can be used for the preparation of high-efficiency solar cells.Superhard material with high hardness, high bulk modulus and high thermal conductivity, are widely used in machinery, electronics, aerospace and other fields. The design and development of superhard material are great significant for the development of modern science and technology. Hardness of diamond is the highest at present. In the process of metal（e.g., Fe, Co, Ni, etc.） material, the diamond is easily deteriorated. Cubic boron nitride（c-BN） overcomes the problem of deterioration of the catalytic, but the cost of the c-BN production is much higher than diamond, and large-scale industrial production is facing difficulties. Recently it was discovered that a high valence electron density of the metal elements（Mo, W, Pt, etc.） and the B, C, N elements combined with each other and synthesized hard compressed metal compounds. Those borides at low load showed superhard characteristic.In this paper, metal Mo film, metal Mo sheet, metal W film, metal W sheet and B4 C powder as starting materials, by high temperature heat treatment technology, we synthesized Mo B,Mo2B4,WB,WB₂ metal borides. The hardness of quenched samples was higher.