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Nonequilibrium Carrier Transport in Quantum Dot Heterostructures.

Accepted version
Peer-reviewed

Type

Article

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Abstract

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.

Description

Keywords

nonequilibrium carrier transport, quantum dots, transient absorption microscopy, ultrafast dynamics

Journal Title

Nano Lett

Conference Name

Journal ISSN

1530-6984
1530-6992

Volume Title

21

Publisher

American Chemical Society (ACS)
Sponsorship
European Research Council (758826)