AI Article Synopsis
- Quantum dot (QD) solids are new materials with potential uses in optoelectronics, and improving their performance requires understanding how energy moves at the nanoscale.
- Researchers studied how connecting individual lead selenide QDs in specific orientations (oriented attachment) impacts their energy dynamics using ultrafast electron diffraction techniques.
- The findings show that when QDs are oriented along ⟨100⟩ directions, energy relaxation and motion are minimized, while along the unattached ⟨111⟩ directions, these effects are heightened, indicating a shift in how heat moves within the material.
Article Abstract
Quantum dot (QD) solids are emerging materials for many optoelectronic applications. To enhance interdot coupling and charge transport, surface ligands can be removed, allowing individual QDs to be attached along specific crystal orientations (termed "oriented attachment"). Optimizing the electronic and optical properties of QD solids demands a comprehensive understanding of the nanoscale energy flow in individual and attached QDs under photoexcitation. In this work, we employed ultrafast electron diffraction to directly measure how oriented attachment along ⟨100⟩ directions affects the nonequilibrium lattice dynamics of lead selenide QDs. The oriented attachment anisotropically alters the ultrafast energy relaxation along specific crystal axes. Along the ⟨100⟩ directions, both the lattice deformation and atomistic random motions are suppressed in comparison with those of individual QDs. Conversely, the effects are enhanced along the unattached ⟨111⟩ directions due to ligand removal. The oriented attachment switches the major lattice thermalization pathways from ⟨100⟩ to ⟨111⟩ directions.
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| http://dx.doi.org/10.1021/acs.jpclett.4c01541 | DOI Listing |
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