量子点
异质结
材料科学
凝聚态物理
物理
非平衡态热力学
量子
光电子学
电子
半导体
弹道传导
量子阱
作者
Mengxia Liu,Sachin Dev Verma,Zhilong Zhang,Jooyoung Sung,Akshay Rao
出处
期刊:Nano Letters
[American Chemical Society]
日期:2021-11-01
卷期号:21 (21): 8945-8951
标识
DOI:10.1021/acs.nanolett.1c01892
摘要
Understanding carrier dynamics and transport in quantum dot based heterostructures is crucial for unlocking their full potential for optoelectronic applications. Here we report the direct visualization of carrier propagation in PbS CQD solids and quantum-dot-in-perovskite heterostructures using femtosecond transient absorption microscopy. We reveal three distinct transport regimes: an initial superdiffusive transport persisting over hundreds of femtoseconds, an Auger-assisted subdiffusive transport before thermal equilibrium is achieved, and a final hopping regime. We demonstrate that the superdiffusive transport lengths correlate strongly with the degree of energetic disorder and carrier delocalization. By tailoring the perovskite content in heterostructures, we obtained a superdiffusive transport length exceeding 90 nm at room temperature and an equivalent diffusivity of up to 106 cm2 s-1, which is 4 orders of magnitude higher than the steady-state values. These findings introduce promising strategies to harness nonequilibrium transport phenomena for more efficient optoelectronic devices.
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