Thermal field structure for casting polycrystalline silicon ingot

Abstract

The invention discloses a thermal field structure for casting a polycrystalline silicon ingot. The thermal field structure comprises a quartz crucible, thermal baffles, heaters, thermal insulating layers and a heat exchange table, wherein the quartz crucible is arranged on the heat exchange table, the thermal baffles are arranged at the periphery of the quartz crucible and are fixed at the bottoms of the side thermal insulating layers, the upper thermal insulating layer and the lower thermal insulating layer are respectively arranged above and below the quartz crucible, the side heaters are arranged between the thermal baffles and the side thermal insulating layers, and the upper heater is arranged between the upper thermal insulating layer and the quartz crucible. The thermal baffles added at the periphery of the quartz crucible enable a long crystal solid liquid interface to be always under the protection of the thermal baffles, reduce the thermal impact of the heaters on a crystal growth interface, and enable crystals to stably grow and inhibit the occurrence of crystal defects; and in the growth process of the crystals, the radiation of the heaters on a solidified silicon ingot is reduced, the latent heat of crystallization is facilitated to be transferred to the heat exchange tale through a solidification part, and the vertical growth of grains is facilitated, thus the conversion efficiency of a polycrystalline silicon solar cell can be effectively improved.

Description

technical field [0001] The invention relates to the field of polycrystalline silicon ingots for solar cells. Background technique [0002] Conventional energy will be exhausted one day, and new energy is destined to wait on the stage of history. Solar energy is an inexhaustible and inexhaustible energy source, and it is also considered to be the most potential alternative to traditional petrochemical energy products. Crystalline silicon cells account for 95% of the solar market, of which polycrystalline silicon cells account for about 70% of crystalline silicon cells. [0003] Polysilicon is mainly produced by directional solidification, that is, the silicon material is melted inside a closed thermal field, and then dissipated heat through the bottom, so that the silicon liquid is gradually solidified upwards to obtain a polysilicon ingot. Cut the silicon ingot into silicon wafers with a thickness of 180um--200um and a size of 156×156mm, which can be used for solar cell man...

AI Technical Summary

Problems solved by technology

However, the polycrystalline silicon wafer produced by this method contains a large number of grain boundaries and micro-defects, and the conversion efficiency of the cell is low. Currently, the conversion efficiency of commercial polycrystalline silicon solar cells is about 17.0%.

[0004] Relatively low conversion efficiency has become the main bottleneck restricting the popula

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