Study Of Metallurgical-grade Polysilicon Surface Texture Of Solar Cells By Alkaline Etching

Low cost NaOH-NaClO3electrolyte was used to fabricate metallurgical-grade polysilicon surface morphology. The effects of ratio of NaOH-NaCLO3, etching temperature and time were investigated. Optimized condition was obtained as following:80℃, NaOH-NaClO3=7:1(wt%),40sec. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) results shown that compact pyramid structure presented at the surface after alkaline etch, acting as a good anti-reflection layer. Reflection spectroscopy indicated that the reflection of the samples treated with NaOH-NaClO3was20.7%,1.8%lower than those treated with HF-HNO3.156*156mm2metallurgical-grade polysilicon solar cells were fabricated with this method. Short circuit current was8.44A, enhanced by3.2%comparing with those fabricated with traditional HF-HNO3treatment. External quantum efficiency (EQE) tests shown that in range of300-650nm, great enhancement was achieved with alkaline etch method, improving the absorption and conversion efficiency of light. In addition, NaOH-NaClO3methods can reduce the cost, because no cooling was needed, which can lower the cost and benefit environmental protection. This study has great potential for large scale application in commercialized production.