Two-step excitation induced photovoltaic properties in an InAs quantum dot-in-well intermediate-band solar cell
Two-step excitation induced photovoltaic properties in an InAs quantum dot-in-well intermediate-band solar cell
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DOI：
10.1063/5.0036313
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发表时间：
2021-02
影响因子：
3.2
通讯作者：
Yaxing Zhu;S. Asahi;Kohei Watanabe;N. Miyashita;Y. Okada;T. Kita
中科院分区：
文献类型：
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作者：
Yaxing Zhu;S. Asahi;Kohei Watanabe;N. Miyashita;Y. Okada;T. Kita
由于亚带隙光子的额外使用，中带太阳能电池被认为是一种有前途的器件设计，可以超越传统光伏器件的转换极限。在独立准费米能级的情况下，这种器件理论上可以保持输出电压。这种现象在实验上表现为由补充的两步光子吸收过程引起的电压恢复。在这里，我们研究了 Al0.3Ga0.7As/GaAs 量子阱中含有 InAs 量子点的中能带太阳能电池的电压性能的激发功率和温度依赖性。采用双色光激发方法分别控制带间跃迁和量子点导带跃迁。输出电压对两种激发密度和电池温度之间的平衡敏感。研究发现，强烈的不对称照射甚至会导致电压下降。与温度相关的数据表明，在较低温度下电子空穴湮灭速度更快。我们引入了一种新的特征指标来定性评估中频段的载波损耗。
Owing to the additional usage of sub-bandgap photons, the intermediate-band solar cell has been regarded as a promising device design to exceed the conversion limits of conventional photovoltaic devices. An output-voltage preservation is theoretically possible in this kind of device in the case of independent quasi-Fermi levels. This phenomenon manifests experimentally in a voltage recovery induced by supplementary two-step photon absorption processes. Here, we study the excitation-power and temperature dependences of the voltage performance in an intermediate-band solar cell containing InAs quantum dots in Al0.3Ga0.7As/GaAs quantum wells. The two-color photoexcitation method is used to separately control the interband and quantum dot-conduction band transitions. The output voltage is sensitive to the balance between the two excitation densities and the cell temperature. It is found that a strongly asymmetric irradiation can even lead to a voltage decrease. The temperature-dependent data suggest a faster electron–hole annihilation at lower temperatures. We introduce a new characteristic index to qualitatively evaluate the carrier loss in the intermediate band.