Multiple Wurtzite Twinning in CdTe Nanocrystals Induced by Methylphosphonic Acid

• Published in: Journal of the American Chemical Society Vol. 128; no. 3; pp. 748 - 755
• Main Authors: Carbone, Luigi, Kudera, Stefan, Carlino, Elvio, Parak, Wolfgang J, Giannini, Cinzia, Cingolani, Roberto, Manna, Liberato
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 25.01.2006
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Growth from solutions; Materials science; Methods of crystal growth; physics of crystal growth; Physics; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Crystal growth; Pseudopotential methods; Theoretical study; Transition elements Compounds; Nanostructures; Experimental study; Transmission electron microscopy; II-VI semiconductors; Cadmium tellurides; Density functional method; Wurtzite structure; Colloidal crystals; Crystal nucleation; Ab initio calculations; Local density approximation; Growth twin
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja054893c

Branching in semiconductor nanocrystals, which leads to tetrapods and to more complex architectures, is the subject of intensive investigation. Here we support the model according to which branching in CdTe nanocrystals is driven by the formation of multiple wurtzite twins. This is in contrast to previous models for this material. We found that twinning, as well as anisotropic growth, can be triggered by the presence of suitable molecules, such as for instance methylphosphonic acid. In the case of CdTe nanocrystals, we designed a robust growth scheme in which the variation of a single parameter (the concentration of methylphosphonic acid in solution) leads to the controlled formation of nanocrystals with shapes ranging from spheres to anisotropic structures with varying level of branching, as both twinning and anisotropic growth are progressively favored. We believe that these concepts can be extended to other nanocrystal systems.