Photocarrier Transport Dynamics in InAs/GaAs Quantum Dot Superlattice Solar Cells Using Time-of-Flight Spectroscopy
Photocarrier Transport Dynamics in InAs/GaAs Quantum Dot Superlattice Solar Cells Using Time-of-Flight Spectroscopy
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使用飞行时间光谱研究 InAs/GaAs 量子点超晶格太阳能电池中的光载流子传输动力学
DOI：
10.1103/physrevb.94.195313
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
and T. Kita
中科院分区：
文献类型：
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作者：
T. Tanibuchi;T. Kada;S. Asahi;D. Watanabe;T. Kaizu;Y. Harada;and T. Kita
我们研究了时间分辨的光载流子输运通过InAs/GaAs量子点超晶格（QDSL）太阳能电池（SC）使用飞行时间光谱与QDSL下的光探针量子点结构。在顶部GaAs层中光泵浦的载流子在到达探针QD之前通过本征层（包括QDSL）传输。光激发载流子密度显著影响量子点和探针量子点的时间分辨光致发光（PL）。探针量子点的时间分辨PL谱表明，激发密度超过大大降低了上升时间，表明快速载流子传输通过量子点。这也得到了QDSL载流子输运动力学的证实，其中激发态的PL强度在该激发功率密度以上迅速衰减，而基态保持恒定。这些结果表明，填充QDSL的基态并开始填充激发态迷你带加速了QDSL SC中的载流子传输。此外，根据用1.3 μm红外激光光源进行的两步光子吸收测量，电子在亚带隙光子照射产生额外光电流中起关键作用。
We studied time-resolved photocarrier transport through InAs/GaAs quantum dot superlattice (QDSL) solar cells (SCs) using time-of-flight spectroscopy with an optical probe QD structure beneath the QDSL. Carriers optically pumped in the top-GaAs layer were transported through the intrinsic layer, including the QDSLs, before arriving at the probe QDs. The photoexcited carrier density significantly influenced the time-resolved photoluminescence (PL) of the QDSLs and probe QDs. The time-resolved PL profile of the probe QDs indicated that excitation densities in excess ofdrastically decreased the rise time, suggesting rapid carrier transport through the QDSLs. This was also confirmed by QDSL carrier transport dynamics, for which the PL intensity of the excited states decayed rapidly above this excitation power density,, while the ground state remained constant. These results demonstrate that filling the ground states of QDSLs and starting to populate the excited state miniband accelerates carrier transport in QDSL SCs. Furthermore, according to two-step photon absorption measurements taken with a 1.3-μm infrared laser light source, electrons play a key role in the generation of extra photocurrent by sub-band-gap photon irradiation.