Peak External Photocurrent Quantum Efficiency Exceeding 100% via MEG in a Quantum Dot Solar Cell
Peak External Photocurrent Quantum Efficiency Exceeding 100% via MEG in a Quantum Dot Solar Cell
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DOI：
10.1126/science.1209845
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发表时间：
2011-12-16
期刊：
影响因子：
56.9
通讯作者：
Beard, Matthew C.
中科院分区：
文献类型：
--
作者：
Semonin, Octavi E.;Luther, Joseph M.;Beard, Matthew C.
多激子产生（MEG）是可以在半导体纳米晶体或量子点（QD）中发生的过程，由此吸收具有至少两倍带隙能量的光子产生两个或更多个电子-空穴对。在这里，我们报告了在基于量子点的硒化铅（PbSe）太阳能电池中由MEG产生的光电流增强，表现为外部量子效率（收集的电荷载流子与入射光子的光谱分辨比），在测量的最佳器件中峰值为114 +/- 1%。相关的内部量子效率（针对反射和吸收损失校正）为130%。我们比较我们的结果与瞬态吸收测量MEG隔离PbSe量子点，并找到合理的协议。我们的研究结果表明，MEG电荷载流子可以收集在适当设计的量子点太阳能电池，提供了充分的激励，以更好地了解MEG内隔离和耦合量子点作为一种研究路径，以提高太阳光收集技术的效率。
Multiple exciton generation (MEG) is a process that can occur in semiconductor nanocrystals, or quantum dots (QDs), whereby absorption of a photon bearing at least twice the bandgap energy produces two or more electron-hole pairs. Here, we report on photocurrent enhancement arising from MEG in lead selenide (PbSe) QD-based solar cells, as manifested by an external quantum efficiency (the spectrally resolved ratio of collected charge carriers to incident photons) that peaked at 114 +/- 1% in the best device measured. The associated internal quantum efficiency (corrected for reflection and absorption losses) was 130%. We compare our results with transient absorption measurements of MEG in isolated PbSe QDs and find reasonable agreement. Our findings demonstrate that MEG charge carriers can be collected in suitably designed QD solar cells, providing ample incentive to better understand MEG within isolated and coupled QDs as a research path to enhancing the efficiency of solar light harvesting technologies.