Optimized short-circuit current mismatch in multi-junction solar cells
Optimized short-circuit current mismatch in multi-junction solar cells
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DOI：
10.1016/j.solmat.2013.05.046
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发表时间：
2013-10
影响因子：
6.9
通讯作者：
M. Bonnet-eymard;M. Boccard;G. Bugnon;F. Sculati‐Meillaud;M. Despeisse;C. Ballif
中科院分区：
文献类型：
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作者：
M. Bonnet-eymard;M. Boccard;G. Bugnon;F. Sculati‐Meillaud;M. Despeisse;C. Ballif
多结光伏器件包括串联电互连的两个或更多个组件子电池。在任何功率点，整个器件的电流输出都受到电流密度最小的子电池的限制。因此，当子电池在它们各自的最大功率点处具有相等的电流密度时，达到最大效率。在这种情况下，子小区被称为“功率匹配”。我们报告了一个实验程序，其中的电流-电压特性的串联太阳能电池可以测量各种辐照光谱下，即在各种短路电流匹配条件下。这允许探测优化的短路电流失配，其中子电池是功率匹配的，这对于定义串联堆的设计规则是必要的。该方法很好地应用于其中一个子电池是亚稳态的器件。我们表明，在薄膜硅串联电池的情况下，光致降解后的最佳失配变化显着。因此，这种设备的退化因子示出不仅取决于材料的质量，但也对初始短路电流匹配。该实验还提供了每个子电池的填充因子的相对定量。我们的实例表明，在以覆层配置沉积的薄膜硅串联电池的情况下，高底部电池沉积速率可能对顶部电池的填充因子有害。
Multi-junction photovoltaic devices include two or more component sub-cells which are electrically interconnected in series. At any power point, the current output of the total device is limited by the sub-cell with the smallest current density. Therefore, the maximum efficiency is reached when the sub-cells have equal current densities at their respective maximum power points. In this case the sub-cells are so called “power matched”. We report an experimental procedure in which the current–voltage characteristics of tandem solar cells can be measured under various irradiance spectra, i.e. under various short-circuit current matching conditions. This permits the probing of the optimized short circuit current mismatch, where the sub-cells are power matched, which is essential to define design rules for the tandem stack. The method applies well to devices where one of the sub-cells is metastable. We show that, in the case of thin-film silicon tandem cells, the optimum mismatch changes significantly after light induced degradation. Consequently, the degradation factor of such devices is shown to depend not only on material quality but also on the initial short circuit current matching. This experiment also provides relative quantification of the fill factors of each sub-cell. Our example suggests that a high bottom cell deposition rate can be detrimental to the fill factor of the top cell in the case of thin-film silicon tandem cells deposited in superstrate configuration.