Requirements for a GaAsBi 1eV sub-cell in a GaAs-based multi-junction solar cell
Requirements for a GaAsBi 1eV sub-cell in a GaAs-based multi-junction solar cell
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DOI：
10.1088/0268-1242/30/9/094010
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发表时间：
2015-09-01
影响因子：
1.9
通讯作者：
Sweeney, S. J.
中科院分区：
文献类型：
--
作者：
Thomas, T.;Mellor, A.;Sweeney, S. J.
多结太阳能电池通过堆叠不同带隙的子电池（通常为GaInP/GaAs/Ge）实现高效率，导致效率超过40%。通过在叠层中引入1 eV的吸收体，或者在三结结构中取代Ge，或者在四结结构中在Ge的顶部上，可以提高效率。GaAs0.94Bi0.06在GaAs上仅产生0.7%应变的1 eV的直接带隙，并且该材料的可行性已经从GaAsBi光电探测器器件中得到证明。GaAsBi的相对高的吸收系数表明可以产生足够的电流以匹配来自标准多结太阳能电池的其他子电池的子电池光电流。然而，少数载流子传输和背景掺杂水平对p/n和p-i-n二极管配置都有限制。在短的少数载流子扩散长度的可能情况下，我们建议使用的p-i-n二极管，并预测的材料参数是必要的，以实现高效率的GaInP/GaAs/GaAsBi/Ge四结电池。
Multi-junction solar cells achieve high efficiency by stacking sub-cells of different bandgaps (typically GaInP/GaAs/Ge) resulting in efficiencies in excess of 40%. The efficiency can be improved by introducing a 1 eV absorber into the stack, either replacing Ge in a triple-junction configuration or on top of Ge in a quad-junction configuration. GaAs0.94Bi0.06 yields a direct-gap at 1 eV with only 0.7% strain on GaAs and the feasibility of the material has been demonstrated from GaAsBi photodetector devices. The relatively high absorption coefficient of GaAsBi suggests sufficient current can be generated to match the sub-cell photocurrent from the other sub-cells of a standard multi-junction solar cell. However, minority carrier transport and background doping levels place constraints on both p/n and p-i-n diode configurations. In the possible case of short minority carrier diffusion lengths we recommend the use of a p-i-n diode, and predict the material parameters that are necessary to achieve high efficiencies in a GaInP/GaAs/GaAsBi/Ge quad-junction cell.