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.     

光伏组件盖板玻璃的结构优化

光伏组件中的玻璃盖板对陷光能力及发电性能有重要影响。本文采用射线追踪的模拟方法,系统研究了盖板玻璃表面减反膜和微结构对组件性能的影响。研究发现,玻璃的内表面结构对器件的光学和电学性能的影响可以忽略。减反膜和玻璃前表面图案都有利于器件性能的提高。玻璃前表面结构为45°金字塔时,光线在空气/玻璃界面能够发生多次反射,同时在光线逃逸出组件时更容易发生全内反射,提高了组件陷光性能。最后研究了不同的入射光角度对不同结构的器件性能的影响。结果表明,金字塔结构在光入射角为0～10°和60～80°时表现出了优异性能,减反膜在光入射角为20～50°时表现更好;当同时使用减反膜和玻璃表面结构时,与平面玻璃相比,每日发电量可以增加5.6%。