偏置控制的InAs / GaAs量子点超晶格中带太阳能电池中高效的两步光生载流子。,Scientific Reports

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偏置控制的InAs / GaAs量子点超晶格中带太阳能电池中高效的两步光生载流子。
Scientific Reports ( IF 3.8 ) Pub Date : 2017-07-19 , DOI: 10.1038/s41598-017-05494-8
T. Kada , S. Asahi , T. Kaizu , Y. Harada , R. Tamaki , Y. Okada , T. Kita

我们研究了内部电场对InAs / GaAs量子点超晶格（QDSL）中带太阳能电池（IBSCs）中两步光载流子产生的影响。QDSL-IBSCs的外部量子效率是内部电场强度的函数，并与考虑了带间和子带间光激发的理论计算结果进行了比较。对于反向偏置的电场，两步光激发引起的额外光电流最大，而带间光激发产生的电流随着电场强度的增加而单调增加。太阳能电池中的内部电场将光生电子和空穴之间的超晶格（SL）微型带分开，该微型带起到中间带的作用，电子寿命延长到微秒级，提高了子带间跃迁强度，因此增加了两步光电流。在增强两步光激发的载流子分离与电场引起的载流子从QDSL逸出之间存在折衷关系。这些结果证明，长寿命电子是最大化QDSL-IBSCs中两步光生载子的关键。

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Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells.

We studied the effects of the internal electric field on two-step photocarrier generation in InAs/GaAs quantum dot superlattice (QDSL) intermediate-band solar cells (IBSCs). The external quantum efficiency of QDSL-IBSCs was measured as a function of the internal electric field intensity, and compared with theoretical calculations accounting for interband and intersubband photoexcitations. The extra photocurrent caused by the two-step photoexcitation was maximal for a reversely biased electric field, while the current generated by the interband photoexcitation increased monotonically with increasing electric field intensity. The internal electric field in solar cells separated photogenerated electrons and holes in the superlattice (SL) miniband that played the role of an intermediate band, and the electron lifetime was extended to the microsecond scale, which improved the intersubband transition strength, therefore increasing the two-step photocurrent. There was a trade-off relation between the carrier separation enhancing the two-step photoexcitation and the electric-field-induced carrier escape from QDSLs. These results validate that long-lifetime electrons are key to maximising the two-step photocarrier generation in QDSL-IBSCs.

更新日期：2017-07-20

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