Ultrafast exciton transport at early times in quantum dot solids
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Authors
Sung, Jooyoung
Toolan, Daniel TW
Han, Sanyang
Pandya, Raj
Weir, Michael P
Xiao, James
Dowland, Simon
Liu, Mengxia
Ryan, Anthony J
Jones, Richard AL
Huang, Shujuan
Journal Title
Nature Materials
ISSN
1476-1122
Publisher
Nature Research
Type
Article
This Version
AM
Metadata
Show full item recordCitation
Zhang, Z., Sung, J., Toolan, D. T., Han, S., Pandya, R., Weir, M. P., Xiao, J., et al. (2022). Ultrafast exciton transport at early times in quantum dot solids. Nature Materials https://doi.org/10.1038/s41563-022-01204-6
Abstract
Quantum dot (QD) solids are an emerging platform for developing a range of optoelectronic devices. Thus, understanding exciton dynamics is essential towards developing and optimizing QD devices. Here, using transient absorption microscopy, we reveal the initial exciton dynamics in QDs with femtosecond timescales. We observe high exciton diffusivity (~10² cm² s¯¹) in lead chalcogenide QDs within the first few hundred femtoseconds after photoexcitation followed by a transition to a slower regime (~10¯¹–1 cm² s¯¹). QD solids with larger interdot distances exhibit higher initial diffusivity and a delayed transition to the slower regime, while higher QD packing density and heterogeneity accelerate this transition. The fast transport regime occurs only in materials with exciton Bohr radii much larger than the QD sizes, suggesting the transport of delocalized excitons in this regime and a transition to slower transport governed by exciton localization. These findings suggest routes to control the optoelectronic properties of QD solids.
Relationships
Is supplemented by: https://doi.org/10.17863/CAM.80070
Sponsorship
Engineering and Physical Sciences Research Council (EP/P027741/1)
Engineering and Physical Sciences Research Council (EP/M006360/1)
Identifiers
External DOI: https://doi.org/10.1038/s41563-022-01204-6
This record's URL: https://www.repository.cam.ac.uk/handle/1810/334130
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