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Oriented-Attachment- and Defect-Dependent PbTe Quantum Dots Growth: Shape Transformations Supported by Experimental
Hugo Rojas-Chávez1, Alan Miralrio2, Heriberto Cruz-Martínez3
1Tecnológico Nacional de México, Instituto Tecnológico de Tláhuac II, Departamento de Ingenierías, Camino Real 625, Col. Jardines del Llano, San Juan Ixtayopan. Alcaldía Tláhuac, CDMX 13508, Mexico.
Inorganic Chemistry
|May 6, 2021
Summary
Mechanisms governing lead telluride quantum dot (PbTe QD) size and shape are revealed. Formaldehyde
Area of Science:
- Materials Science
- Nanotechnology
- Physical Chemistry
Background:
- Monodispersed lead telluride quantum dots (PbTe QDs) are crucial for advanced electronic and optoelectronic applications.
- Understanding the synthesis mechanisms that control PbTe QD size and shape is essential for tailored material properties.
Purpose of the Study:
- To elucidate the oriented-attachment and defect-dependent mechanisms governing PbTe QD size and shape evolution.
- To investigate the role of formaldehyde in the mechanochemical synthesis of monodispersed PbTe QDs.
- To theoretically explore the interactions between formaldehyde and PbTe surfaces.
Main Methods:
- High-resolution transmission electron microscopy (HRTEM) for visualizing QD morphology.
- Dispersion-corrected density functional theory (DFT) calculations for electronic structure and adsorption.
- Fukui function and Lowdin charge analysis to determine surface reactivity.
- Modified Wulff construction to predict equilibrium crystal shapes.
Main Results:
- Oriented-attachment mechanisms lead to quasi-cubic PbTe QDs, while defect-dependent mechanisms yield decahedral QDs (~6 nm).
- Formaldehyde was identified as a critical parameter in the mechanochemical synthesis of monodispersed PbTe QDs.
- DFT calculations confirmed Pb surface atoms as reactive sites for nucleophilic attack by formaldehyde, with significant adsorption energies.
- Theoretical models predicted decahedral shapes due to (111) facets and other shapes influenced by (100), (110), and (111) facets.
Conclusions:
- The study reveals distinct mechanisms controlling PbTe QD morphology, influenced by lattice defects and facet-specific growth.
- Formaldehyde plays a key role in PbTe QD synthesis, interacting electrostatically with Pb surface atoms.
- Theoretical insights support the observed QD shapes and highlight the importance of facet energies and surface interactions.
