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Chemically triggered formation of two-dimensional epitaxial quantum dot superlattices

(2016) ACS NANO. 10(7). p.6861-6870
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Abstract
Two dimensional superlattices of epitaxially connected quantum dots enable size-quantization effects to be combined with high charge carrier mobilities, an essential prerequisite for highly performing QD devices based on charge transport. Here, we demonstrate that surface active additives known to restore nanocrystal stoichiometry can trigger the formation of epitaxial superlattices of PbSe and PbS quantum dots. More specifically, we show that both chalcogen-adding (sodium sulfide) and lead oleate displacing (amines) additives induce small area epitaxial superlattices of PbSe quantum dots. In the latter case, the amine basicity is a sensitive handle to tune the superlattice symmetry, with strong and weak bases yielding pseudohexagonal or quasi-square lattices, respectively. Through density functional theory calculations and in situ titrations monitored by nuclear magnetic resonance spectroscopy, we link this observation to the concomitantly different coordination enthalpy and ligand displacement potency of the amine. Next to that, an initial similar to 10% reduction of the initial ligand density prior to monolayer formation and addition of a mild, lead oleate displacing chemical trigger such as aniline proved key to induce square superlattices with long-range, square micrometer order; an effect that is the more pronounced the larger the quantum dots. Because the approach applies to PbS quantum dots as well, we conclude that it offers a reproducible and rational method for the formation of highly ordered epitaxial quantum dot superlattices.
Keywords
surface chemistry, SEMICONDUCTOR-NANOCRYSTAL SUPERLATTICES, quantum-dot solid, self-assembly, PbSe, nanomaterials, MONO LAYERS, PBSE NANOCRYSTALS, SURFACE-CHEMISTRY, LIGAND-EXCHANGE, COLLOIDAL NANOCRYSTALS, ELECTRON TOMOGRAPHY, LIQUID-AIR INTERFACE, FIELD-EFFECT TRANSISTORS, ENTROPY-DRIVEN FORMATION

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Citation

Please use this url to cite or link to this publication:

Chicago
Walravens, Willem, Jonathan De Roo, Emile Drijvers, Stephanie ten Brinck, Eduardo Solano Minuesa, Jolien Dendooven, Christophe Detavernier, Ivan Infante, and Zeger Hens. 2016. “Chemically Triggered Formation of Two-dimensional Epitaxial Quantum Dot Superlattices.” Acs Nano 10 (7): 6861–6870.
APA
Walravens, W., De Roo, J., Drijvers, E., ten Brinck, S., Solano Minuesa, E., Dendooven, J., Detavernier, C., et al. (2016). Chemically triggered formation of two-dimensional epitaxial quantum dot superlattices. ACS NANO, 10(7), 6861–6870.
Vancouver
1.
Walravens W, De Roo J, Drijvers E, ten Brinck S, Solano Minuesa E, Dendooven J, et al. Chemically triggered formation of two-dimensional epitaxial quantum dot superlattices. ACS NANO. 2016;10(7):6861–70.
MLA
Walravens, Willem, Jonathan De Roo, Emile Drijvers, et al. “Chemically Triggered Formation of Two-dimensional Epitaxial Quantum Dot Superlattices.” ACS NANO 10.7 (2016): 6861–6870. Print.
@article{8066052,
  abstract     = {Two dimensional superlattices of epitaxially connected quantum dots enable size-quantization effects to be combined with high charge carrier mobilities, an essential prerequisite for highly performing QD devices based on charge transport. Here, we demonstrate that surface active additives known to restore nanocrystal stoichiometry can trigger the formation of epitaxial superlattices of PbSe and PbS quantum dots. More specifically, we show that both chalcogen-adding (sodium sulfide) and lead oleate displacing (amines) additives induce small area epitaxial superlattices of PbSe quantum dots. In the latter case, the amine basicity is a sensitive handle to tune the superlattice symmetry, with strong and weak bases yielding pseudohexagonal or quasi-square lattices, respectively. Through density functional theory calculations and in situ titrations monitored by nuclear magnetic resonance spectroscopy, we link this observation to the concomitantly different coordination enthalpy and ligand displacement potency of the amine. Next to that, an initial similar to 10\% reduction of the initial ligand density prior to monolayer formation and addition of a mild, lead oleate displacing chemical trigger such as aniline proved key to induce square superlattices with long-range, square micrometer order; an effect that is the more pronounced the larger the quantum dots. Because the approach applies to PbS quantum dots as well, we conclude that it offers a reproducible and rational method for the formation of highly ordered epitaxial quantum dot superlattices.},
  author       = {Walravens, Willem and De Roo, Jonathan and Drijvers, Emile and ten Brinck, Stephanie and Solano Minuesa, Eduardo and Dendooven, Jolien and Detavernier, Christophe and Infante, Ivan and Hens, Zeger},
  issn         = {1936-0851},
  journal      = {ACS NANO},
  keyword      = {surface chemistry,SEMICONDUCTOR-NANOCRYSTAL SUPERLATTICES,quantum-dot solid,self-assembly,PbSe,nanomaterials,MONO LAYERS,PBSE NANOCRYSTALS,SURFACE-CHEMISTRY,LIGAND-EXCHANGE,COLLOIDAL NANOCRYSTALS,ELECTRON TOMOGRAPHY,LIQUID-AIR INTERFACE,FIELD-EFFECT TRANSISTORS,ENTROPY-DRIVEN FORMATION},
  language     = {eng},
  number       = {7},
  pages        = {6861--6870},
  title        = {Chemically triggered formation of two-dimensional epitaxial quantum dot superlattices},
  url          = {http://dx.doi.org/10.1021/acsnano.6b02562},
  volume       = {10},
  year         = {2016},
}

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