原子层沉积氧化铝薄膜对多晶太阳能电池表面钝化的影响

A stack of Al2O3/SiNx dual layer was applied for the back side surface passivation of p-type multi-crystalline silicon solar cells, with laser-opened line metal contacts, forming a local aluminum back surface field （local Al-BSF） structure. A slight amount of Al2O3, wrapping around to the front side of the wafer during the thermal atomic layer deposition process, was found to have a negative influence on cell performance. The different process flow was found to lead to a different cell performance, because of the Al2O3 wrapping around the front surface. The best cell performance, with an absolute efficiency gain of about 0.6% compared with the normal full Al-BSF structure solar cell, was achieved when the Al2O3 layer was deposited after the front surface of the wafer had been covered by a SiNx layer. We discuss the possible reasons for this phenomenon, and propose three explanations as the Ag paste, being hindered from firing through the front passivation layer, degraded the SiNx passivation effect and the Al2O3 induced an inversion effect on the front surface. Characterization methods like internal quantum efficiency and contact resistance scanning were used to assist our understanding of the underlying mechanisms.     

高效率n型Si太阳电池技术现状及发展趋势

提高太阳电池光电转换效率、降低光伏发电成本已成为全球光伏领域的研究热点。由于n型晶体Si具有体少子寿命长、光致衰减小等优点,非常适于制作低成本高效率太阳电池,近年来高效率n型Si太阳电池引起了人们广泛的关注。文章在论述n型Si特性的基础上,介绍了IBC结构、PERT结构、HIT结构、PERL结构和常规电池结构n晶体Si太阳电池的研究进展及产业化水平,给出了n型Si电池今后的研究方向。