Effects of Impurity Barrier Layer on the Red Zone at the Bottom of Cast Monocrystalline Si Ingot for Solar Cells

Abstract

A technique to prepare low‐cost high‐purity quartz sheets as impurity barrier layers between the crucible and the seed crystal is proposed herein to improve the casting process of monocrystalline Si (mono‐Si) ingots. The results show that the diffusion of metal impurities from the crucible toward a cast mono‐Si ingot can be hindered, increasing the minority carrier lifetime of Si crystals and reducing the height of the red zone at the bottom of the ingot. Solar cell devices assembled from cast mono‐Si ingots exhibit the enhancement in their overall photoelectric conversion efficiency (η) by 0.76% in comparison to those based on conventional mono‐Si ingots. Therefore, high‐purity quartz sheets as impurity barrier layers for the casting of mono‐Si ingots have great application potential in the photovoltaic industry.