Two-step photon up-conversion solar cells.
Two-step photon up-conversion solar cells.
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DOI：
10.1038/ncomms14962
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发表时间：
2017-04-06
影响因子：
16.6
通讯作者：
Kita T
中科院分区：
文献类型：
--
作者：
Asahi S;Teranishi H;Kusaki K;Kaizu T;Kita T
降低带隙下光子的传输损耗是突破太阳能电池能量转换效率极限的直接途径。带隙下光子的上转换对于产生额外的光电流是非常有希望的。在这里，我们提出了一个两步光子上转换SC异质界面包括不同的带隙的Al 0.3Ga 0.7As和GaAs。Al0.3Ga0.7As的禁带下光子激发GaAs并在异质界面产生电子。在异质界面处积累的电子被向上泵浦到Al 0.3Ga 0.7As势垒中，由GaAs的带隙下光子泵浦。通过在异质界面引入InAs量子点实现了高效的两步光子上转换。我们观察到不仅在额外的光电流，超过了约两个数量级的报道值的急剧增加，而且在光电压的增加。这些结果表明，两步光子上转换SC在下一代高效SC中具有很高的实现潜力。收集具有低于带隙的能量的入射光子可以导致高效的太阳能电池。通过在异质界面处引入InAs量子点，Asahi等人实现了有效的两步光子上转换，从而产生额外的光电流和非常高的外量子效率。
Reducing the transmission loss for below-gap photons is a straightforward way to break the limit of the energy-conversion efficiency of solar cells (SCs). The up-conversion of below-gap photons is very promising for generating additional photocurrent. Here we propose a two-step photon up-conversion SC with a hetero-interface comprising different bandgaps of Al0.3Ga0.7As and GaAs. The below-gap photons for Al0.3Ga0.7As excite GaAs and generate electrons at the hetero-interface. The accumulated electrons at the hetero-interface are pumped upwards into the Al0.3Ga0.7As barrier by below-gap photons for GaAs. Efficient two-step photon up-conversion is achieved by introducing InAs quantum dots at the hetero-interface. We observe not only a dramatic increase in the additional photocurrent, which exceeds the reported values by approximately two orders of magnitude, but also an increase in the photovoltage. These results suggest that the two-step photon up-conversion SC has a high potential for implementation in the next-generation high-efficiency SCs. Harvesting incident photons with energy below the bandgap may lead to highly efficient solar cells. By introducing InAs quantum dots at the hetero-interface, Asahi et al. achieve efficient two step photon up-conversion resulting in additional photocurrent and very high external quantum efficiency.