硅氧合金薄膜及其在高效纳米硅薄膜叠层太阳电池中的应用研究

SILICON-OXIDE ALLOY THIN FILMS AND THEIR APPLICATION IN HIGH EFFICIENCY NANOCRYSTALLINE SILICON TANDEM SOLAR CELL

系统研究两种不同形态的硅氧合金薄膜,用甚高频PECVD系统制备的非晶硅氧和纳米硅氧薄膜的特性,以及其在纳米硅薄膜叠层薄膜太阳电池中的应用。实验中主要通过对不同的气体流量比的优化、沉积功率和沉积压力的优化,分别制备出光学带隙约为2.1 e V,折射率约为3的a-SiO_x∶B∶H薄膜,作为非晶硅顶电池的p1层,以及带隙为2.2~2.5 e V,折射率为2.0~2.5,晶化率为20%~50%的nc-SiO_x∶P∶H薄膜,作为非晶硅/纳米硅叠层电池的中间反射层和纳米硅的底电池n2层。最后将优化后的a-SiO_x∶B∶H和nc-SiO_x∶P∶H薄膜应用到非晶硅/纳米硅薄膜叠层电池中,在0.79 m^2的玻璃基板上制备出初始峰值功率为101.1 W、全面积初始转换效率为12.8%、稳定峰值功率为87.3 W、全面积稳定转换效率为11.1%的非晶硅/纳米硅叠层电池。

The properties of two types of silicon-oxide alloys, amorphous silicon-oxide （a-SiOx） and nanocrystalline silicon oxide （nc-SiOx） prepared by using very high frequency （VHF） plasma enhanced chemical vapor deposition （CVD） system, and their application in amorphous silicon and nanocrytalline silicon （a-Si/nc-Si） double junction solar cells were studied. The a-SiOx and nc-SiO, films were obtained by optimizing gas flow ratio, RF power and deposition pressure as follows： 1 ） a-SiOx： B：H films with bandgap of 2.1 eV, and refractive index of 3, which was used as P1 layer of a-Si top cell, and 2） nc-SiOx： P： H films with bandgap of 2.2-2.5 eV, refractive index of 2.0-2.5, and crystallization fraction of 25%-40%, which was used for both middle reflection layer of a-Si/nc-Si tandem solar cell, and n2 layer of nc- Si bottom cells. Eventually, the optimal SiOx： B：H and nc-SiOx：P： H films were used to prepare a-Si/nc-Si tandem solar cells on glass substrate of 0.79 m2, with initial Pmax of 101.1 W, corresponding to 12.8% total area initial efficiency, and stabilized Pmax of 87.3 W, corresponding to 11.1% stable efficiency. Keywords：