Ion-implanted high-efficiency solar cells on cast monocrystalline silicon

This paper demonstrates high-efficiency solar cells made on commercial grade cast monocrystalline (cast-mono) silicon using ion implantation. 18.9% efficient solar cells on 156 mm square cast-mono wafers from Canadian Solar are fabricated featuring an oxide passivated emitter, aluminum back-surface field and full industrial processing. Further investigation revealed that the cast-mono cells can benefit from the increased short-circuit current density due to random pyramid texture, compared to isotexture, even down to 60% area of <100> grain on a wafer. This paper highlights the importance of improving the quality and yield of cast-mono wafers and the benefits of ion implant technology to produce high-efficiency cast-mono cells at lower cost. Also highlighted is the importance of increased light trapping from alkaline texture of cast-mono wafers.