Enhanced separation of bulk silicon from Si-Sn melt via electromagnetic directional solidification

Developing new methods for solar photovoltaic power generation is an effective way to solve future energy shortages. Solvent refining is one of the most promising methods to achieve the low-cost mass production of solar-grade Si. In this work, a novel method for separating bulk silicon from a Si-Sn melt under intensification by an electromagnetic stirring is proposed. The growth and enrichment of Si crystals were controlled by the upward and downward directional solidification of Si-50at%Sn melt at different moving rates. Compared with traditional directional solidification, electromagnetic stirring yielded a higher growth rate of Si. A lower moving rate improved the enrichment percentage of Si, and a large area of bulk Si with an enrichment percentage of up to 88.16% was obtained by performing downward directional solidification at a rate of 3 µm/s. Moreover, the downward movement improved the Si enrichment, because Si grew along the bottom and side walls of the crucible. These results provide a new scientific perspective and experimental evidence for the separation of primary Si crystals from Si-based multicomponent solvents.