Study On The Preparation Of The Cordierite-silicon Multiphase Ceramic Substrate Used For Solar Cells

Polycrystalline silicon thin film solar cells has the characteristics of high cell efficiency and stable performance, and the cost of polycrystalline silicon thin film solar cells is low due to the use of thin materials. It is the focus study of silicon thin film solar cells. Polycrystalline silicon thin film is composed of many small grains with different grain orientation which are grown on substrates. Polycrystalline silicon thin film solar cells can be divided into low-temperature line and high-temperature line in accordance with deposition conditions. In the low temperature deposition, glass and plastic materials can be chosen as substrates. But the deposition size of thin film grain is small, the deposition quality is poor and the cell efficiency is very low. Though high-temperature deposition has good quality and big thin film grain size despite of energy consumption, there is no proper substrate used for high-temperature deposition of polycrystalline silicon thin film solar cells. Therefore, the study of suitable substrate for high-temperature deposition is of great significance for promoting the development and application of the polycrystalline silicon thin film solar cells.In this paper, the preparation of cordierite-silicon multiphase ceramic substrates were studied, cordierite has good high temperature resistance, chemical stability and thermal coefficient which is close to that of silicon. So it could be used as the high temperature substrate. The multiphase ceramic itself is a kind of gradient material according to the silicon concentration level, which would be no heat matching problem. It’s an ideal substrate that hasn’t been studied by now. There are three parts in the paper.The first part is the synthesis of cordierite powders that were used as the raw material for the following experiment. Flint clay, bauxite and talc were used as the starting materials. The optimal preparation temperature was1280℃by means of XRD and DTA results in this raw material system. The second part is the preparation of cordierite ceramics using the raw material from the first part. The preparation of the cordierite ceramics is about1400℃and the melting point is1460℃, so the sintering range is narrow. Meanwhile the preparation temperature must be below the melting point of silicon that is1420℃, because of preventing silicon penetration into cordierite. Therefore, lowing the preparation temperature of cordierite ceramic was firstly studied. The tape casting and pressure molding were adopted in this part. The influence of Y2O3and Bi2O3used as sintering aids were also discussed. The cordierite ceramic adopting casting molding had a higher water absorption than adopting compression molding. The cordierite ceramic adopting pressure molding had the smallest water absorption that was5.9%.The third part is the preparation of the cordierite-silicon multiphase ceramic substrate. The green sheets prepared by pressure molding were sintered in nitrogen atmosphere furnace. The optimal preparation temperature was1390℃by analyzing the relative performances.