Quantum wells for high-efficiency photovoltaics
Quantum wells for high-efficiency photovoltaics
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用于高效光伏发电的量子阱
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
N. Ekins‐Daukes
中科院分区：
文献类型：
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作者：
D. Alonso‐Álvarez;N. Ekins‐Daukes
在过去的几十年里，人们对应变平衡半导体量子威尔斯（QW）进行了深入的研究，以提高在锗上单片生长的多结太阳能（MJ）太阳能电池的效率。到目前为止，量子阱的最成功的应用只需要定制几十纳米的吸收边的一个给定的子电池，以达到最佳的光谱位置。然而，对需要3个、4个或更多个结的更高效率器件的需求代表了量子阱必须面对的挑战的主要差异：定制主体材料的吸收边缘是不够的，必须设计一个全新的器件，吸收不同光谱区域的光。需要解决的最重要的问题之一是需要光学厚结构来吸收足够的光，同时使用高度应变的材料保持优异的载流子提取。在过去的几年里，生长技术的改进，更智能的器件设计-例如涉及超晶格和移位量子阱-或者使用量子线而不是量子阱，已经被证明是实现基于纳米结构的高效MJ太阳能电池的非常有效的步骤。但要达到目标业绩，还有更多的工作要做。这项工作讨论了所有这些挑战，它们所代表的限制以及用于克服它们的不同方法。
Over the last couple of decades, there has been an intense research on strain balanced semiconductor quantum wells (QW) to increase the efficiency of multi-junction solar (MJ) solar cells grown monolithically on germanium. So far, the most successful application of QWs have required just to tailor a few tens of nanometers the absorption edge of a given subcell in order to reach the optimum spectral position. However, the demand for higher efficiency devices requiring 3, 4 or more junctions, represents a major difference in the challenges QWs must face: tailoring the absorption edge of a host material is not enough, but a complete new device, absorbing light in a different spectral region, must be designed. Among the most important issues to solve is the need for an optically thick structure to absorb enough light while keeping excellent carrier extraction using highly strained materials. Improvement of the growth techniques, smarter device designs - involving superlattices and shifted QWs, for example - or the use of quantum wires rather than QWs, have proven to be very effective steps towards high efficient MJ solar cells based on nanostructures in the last couple of years. But more is to be done to reach the target performances. This work discusses all these challenges, the limitations they represent and the different approaches that are being used to overcome them.