Controlling Nanocrystal Superlattice Symmetry and Shape-Anisotropic Interactions through Variable Ligand Surface Coverage
Controlling Nanocrystal Superlattice Symmetry and Shape-Anisotropic Interactions through Variable Ligand Surface Coverage
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DOI：
10.1021/ja110454b
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发表时间：
2011-03-09
影响因子：
15
通讯作者：
Hanrath, Tobias
中科院分区：
文献类型：
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作者：
Choi, Joshua J.;Bealing, Clive R.;Hanrath, Tobias
胶体纳米晶(NCs)组装成具有长程平移和取向有序性的超结构对结合在NC表面的配体之间的分子相互作用非常敏感。我们说明了如何利用胶体PbS纳米碳管上的配体覆盖率作为可调参数来指导具有预定对称性的超晶格的自组装。结果表明，具有密集配体覆盖率的PbS纳米碳管组装成面心立方(FCC)超晶格，而具有稀疏配体覆盖率的PbS纳米碳管组装成体心立方(BCC)超晶格，这些超晶格在其晶格位置上也表现出NCS的取向有序。表面化学表征结合密度泛函理论计算表明，配体的丢失优先发生在{100}面上，而不是重构的{111}面上。由此产生的各向异性配体分布放大了NC形状在组装中的作用，并导致了具有平移和取向顺序的超晶格的形成。
The assembly of colloidal nanocrystals (NCs) into superstructures with long-range translational and orientational order is sensitive to the molecular interactions between ligands bound to the NC surface. We illustrate how ligand coverage on colloidal PbS NCs can be exploited as a tunable parameter to direct the self-assembly of superlattices with predefined symmetry. We show that PbS NCs with dense ligand coverage assemble into face-centered cubic (fcc) superlattices whereas NCs with sparse ligand coverage assemble into body-centered cubic (bcc) superlattices which also exhibit orientational ordering of NCs in their lattice sites. Surface chemistry characterization combined with density functional theory calculations suggest that the loss of ligands occurs preferentially on {100} than on reconstructed {111} NC facets. The resulting anisotropic ligand distribution amplifies the role of NC shape in the assembly and leads to the formation of superlattices with translational and orientational order.