Impact of front-side point contact/passivation geometry on thin-film solar cell performance
Impact of front-side point contact/passivation geometry on thin-film solar cell performance
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DOI：
10.1016/j.solmat.2017.02.031
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发表时间：
2017-06-01
影响因子：
6.9
通讯作者：
Tiwari, Ayodhya N.
中科院分区：
文献类型：
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作者：
Sozzi, Giovanna;Di Napoli, Simone;Tiwari, Ayodhya N.
在这项工作中，我们对CIGS太阳能电池结构进行了广泛的三维数值模拟，以研究具有点接触开口的表面钝化CIGS对电池性能参数（J(sc), V-oc， FF和eta）的影响。在高度缺陷的CIGS前表面和理想化学钝化假设下，对钝化厚度、点接触尺寸和节距的组合进行了详细分析：通过优化的纳米尺度点接触阵列可以实现接近理想（即无缺陷）CdS/CIGS界面的效率。为了解释钝化层内由于正剩余电荷密度Q(f)引起的场效应钝化，我们在理想和无效化学钝化两种极端情况下，在1010-1013 cm（-2）范围内改变Q(f)。本文还分析了几种具有不同缓冲层（CdS、ZnO、ZnMgO、In2S3、Zn(O， S)）的CIGS电池。我们发现，在1012 -5.10(12)cm（-2）区间内的正Q(f)可以帮助完全恢复理想的电池效率，而不考虑化学钝化效应，甚至在缓冲/CIGS异质结处存在不利的导带取向。这可能有助于设计替代cd的缓冲材料的解决方案，从而提高表面受限电池的性能。晶界缺陷密度和位置对点接触的影响也得到了解决，晶粒尺寸为750nm。
In this work, we perform an extensive campaign of three-dimensional numerical simulations of CIGS solar cell structures to investigate the effect of a surface-passivated CIGS with point contacts openings on the cell performance parameters (J(sc), V-oc, FF and eta). Detailed analysis of the combination of passivation thickness, point contact size and pitch is performed under the hypothesis of highly defective CIGS front surface and ideal chemical passivation: efficiencies close to the case of ideal (i.e., defect-free) CdS/CIGS interface can be achieved by optimized nanometer-scale point contact arrays. To account for field-effect passivation due to positive residual charge density, Q(f) within the passivation layer, we vary Q(f) in the range 1010-1013 cm(-2) under the two extreme scenarios of ideal or ineffective chemical passivation. Several examples of CIGS cells with different buffer layers (CdS, ZnO, ZnMgO, In2S3, Zn(O, S)) are also analyzed. We find that a positive Q(f) in the interval 1012 -5.10(12) cm(-2) can help completely recover the ideal cell efficiency, irrespective of the chemical passivation effect and even in the presence of unfavorable conduction band alignment at the buffer/CIGS heterojunction. This may help devising solutions with buffer materials alternative to CdS, boosting the performance of otherwise surface-limited cells. The effect of grain boundary defect density and position with respect to point contacts is also addressed, with a grain dimension of 750 nm.