光激发
多激子产生
太阳能电池
量子点
光电子学
带隙
激发
量子阱
太阳能电池理论
光伏系统
费米能级
宽禁带半导体
材料科学
砷化镓
电子
凝聚态物理
物理
太阳能电池效率
光学
激光器
电气工程
量子力学
工程类
作者
Yaxing Zhu,Shigeo Asahi,Kohei Watanabe,Naoya Miyashita,Yoshitaka Okada,Takashi Kita
摘要
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.
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