Numerical simulation of the impurity photovoltaic effect in silicon solar cells
Numerical simulation of the impurity photovoltaic effect in silicon solar cells
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DOI：
10.1016/j.renene.2007.05.027
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发表时间：
2008-02
期刊：
影响因子：
8.7
通讯作者：
S. Khelifi;J. Verschraegen;M. Burgelman;A. Belghachi
中科院分区：
文献类型：
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作者：
S. Khelifi;J. Verschraegen;M. Burgelman;A. Belghachi
最近，人们提出利用杂质光伏效应(IPV)来改善太阳能电池的性能。自由电子-空穴对可以通过两步过程产生，包括能隙中的杂质能级和两个较低能量的光子：首先，电子被光学激发，从价带到缺陷能级，然后从缺陷能级到导带。因此，IPV效应将增强细胞的长波响应。文献中对IPV效应进行了大量的理论研究，特别是对含铟杂质的硅太阳电池。然而，缺乏一个容易获得的包含IPV效应的太阳能电池模拟器是一个障碍。在这项工作中，扩展了ELIS组的数值太阳能电池模拟器SAVS，以包括ELIS组和LPDS组之间的合作的IPV。实现了一些特殊功能，如利用Lucovsky模型计算了杂质的电子和空穴光电发射截面。对照文献中的现有结果对新的Savs版本的功能进行了检查。此外，还给出了太阳电池参数随铟密度变化的新结果。我们发现，增加铟浓度可以改善硅太阳电池的参数，特别是短路电流和效率，而不会显著降低开路电压。如果为细胞选择了合适的结构，这是可能的。最佳的铟密度应在基区密度附近相等，才能从IPV效应中获得正的好处。光陷阱在IPV研究中非常重要，它与电池正面和背面的内部反射有关。前后反射率应超过99.9%，才能获得真正的效率提高。我们计算出，由于IPV效应增强了长波长吸收，光电流提高了约6 mA/cm2，效率提高了约2%。
Recently, the impurity photovoltaic effect (IPV) was proposed to improve the solar cell performance. Free electron–hole pairs can be generated in a two-step process involving an impurity level in the energy gap and two lower-energy photons: first electrons are optically excited from the valence band to the defect level and then from the defect level to the conduction band. The IPV effect will thus enhance the long-wavelength response of the cell. A significant amount of theoretical work has been carried out on IPV effect in the literature, particularly on silicon solar cells with indium impurities as defect. However, the lack of an easily available solar cell simulator including the IPV effect is a handicap. In this work, the numerical solar cell simulator SCAPS of the ELIS group was extended to include IPV in collaboration between the ELIS and the LPDS groups. Also, some special features are implemented, such as the calculation of electron and hole photoemission cross-sections of the impurity using the model of Lucovsky. The functionality of new SCAPS version was checked against existing results in the literature. Also, new results are presented such as the evolution of solar cell parameters with the indium density. We find that increasing indium concentration can improve silicon solar cell parameters, especially the short-circuit current and the efficiency, without drastically decreasing the open-circuit voltage. This is possible if a suitable structure for the cell is chosen. The optimum indium density should be equal around the base region density to obtain a positive benefit from the IPV effect. Light trapping, which is related to the internal reflectance at the front and the back of the cell, is very important in the IPV study. Reflectivity at the front and the back should exceed 99.9% to obtain a real efficiency increase. We calculate an improvement of about 6mA/cm2in the photocurrent, and about 2% for the efficiency, which is due to the enhancement of long-wavelength absorption by the IPV effect.