Higher quality mono-like cast silicon with induced grain boundaries

• Published in: Solar energy materials and solar cells Vol. 140; pp. 121 - 125
• Main Authors: Hu, Dongli, Yuan, Shuai, He, Liang, Chen, Hongrong, Wan, Yuepeng, Yu, Xuegong, Yang, Deren
• Format: Journal Article
• Language: English
• Published: 01-09-2015
• Subjects: Dislocations; Grain boundaries; Ingot casting; Ingots; Minority carriers; Photovoltaic cells; Silicon; Solar cells
• ISSN: 0927-0248
• DOI: 10.1016/j.solmat.2015.03.027

Sub-grain boundaries related to dislocation clusters are seriously detrimental to the quality of mono-like cast silicon, which reduce the efficiency of the solar cells. Here, we have developed a novel technique to grow the mono-like cast silicon by forming special grain boundaries. The special grain boundaries are induced by controlling the placing method of seeds at the bottom of crucible. It is found that the subgrain boundaries in the new ingots are completely suppressed, which are clarified by the measurements of photoluminescence and electroluminescence. Therefore, compared to the conventional mono-like ingot, the minority carrier lifetime of the new ingots is significantly increased, and the internal quantum efficiency of corresponding solar cells gets obviously improved. As a result, the power conversion efficiency of the solar cells is averagely 18.1%, which is much higher than that of conventional ones by a value of 0.6% absolutely. These results are of significance for the quality improvement of mono-like silicon and their application in photovoltaics.