Bifunctional Hybrid a-SiO x(Mo) Layer for Hole-Selective and Interface Passivation of Highly Efficient MoO x/a-SiO x(Mo)/n-Si Heterojunction Photovoltaic Device.
Bifunctional Hybrid a-SiO x(Mo) Layer for Hole-Selective and Interface Passivation of Highly Efficient MoO x/a-SiO x(Mo)/n-Si Heterojunction Photovoltaic Device.
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DOI：
10.1021/acsami.8b07001
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发表时间：
2018-07
影响因子：
9.5
通讯作者：
M. Gao;Dong-Yun Chen;Baichao Han;Wenlei Song;Miao Zhou;Xiaomin Song;F. Xu;Lei Zhao;
中科院分区：
文献类型：
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作者：
M. Gao;Dong-Yun Chen;Baichao Han;Wenlei Song;Miao Zhou;Xiaomin Song;F. Xu;Lei Zhao;
为了实现空穴和电子选择性钝化接触，分别采用了正面织构化的氧化铟锡/MoOx结构和背面平坦化的a-SiOx/poly（Si（n+））结构，构建了具有应用前景的n-Si基太阳能电池。简单的MoOx/n-Si异质结器件获得了16.7%的效率。通过高分辨透射电子显微镜和X射线能谱分析，发现在MoOx/n-Si界面处，未经预氧化就形成了SiOx（Mo）三元混合过渡层（3.5- 4.0nm），该过渡层为非晶态结构。X射线光电子能谱（XPS）分析表明，MoOx膜中低氧化态的产生表明，SiOx与Mo元素在中间层中呈梯度分布，起到了钝化硅衬底的作用。密度泛函理论计算表明，在三元混合a-SiO x（Mo）中间层中存在两个与Mo组分有关的半填充能级（局域态）和三个未占据能级（扩展态），它们分别对光生空穴起缺陷辅助隧穿和直接隧穿的作用.用隧道复合模型很好地描述了MoOx/n-Si异质结器件中光生空穴的输运过程。同时，在器件背面组装了a-SiOx/poly（Si（n+））结构，用于直接隧穿光生电子和阻挡光生空穴。
The promising n-Si-based solar cell is constructed for the purpose of realizing hole- and electron-selective passivating contact, using a textured front indium tin oxide/MoO x structure and a planar rear a-SiO x/poly(Si(n+)) structure severally. The simple MoO x/n-Si heterojunction device obtains an efficiency of 16.7%. It is found that the accompanying ternary hybrid SiO x(Mo) interlayer (3.5-4.0 nm) is formed at the MoO x/n-Si boundary zone without preoxidation and is of amorphous structure, which is determined by a high-resolution transmission electron microscope with energy-dispersive X-ray spectroscopy mapping. The creation of lower-oxidation states in MoO x film indicates that the gradient distribution of SiO x with Mo element occurs within the interlayer, acting as a passivation of silicon substrate, which is revealed by X-ray photoelectron spectroscopy with depth etching. Specifically, calculations by density functional theory manifest that there are two half-filled levels (localized states) and three unoccupied levels (extended states) relating to Mo component in the ternary hybrid a-SiO x(Mo) interlayer, which play the roles of defect-assisted tunneling and direct tunneling for photogenerated holes, respectively. The transport process of photogenerated holes in the MoO x/n-Si heterojunction device is well-described by the tunnel-recombination model. Meanwhile, the a-SiO x/poly(Si(n+)) has been assembled on the rear of the device for direct tunneling of photoinduced electrons and blocking photoinduced holes.