Colloidal nanocrystals as LEGO® bricks for building electronic band structure models

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Self-assembled semiconductor nanocrystal (NC) superlattices are a rapidly developing research area.
• Oriented attachment has yielded various NC superlattice structures like chains, square lattices, and honeycomb lattices.
• Lead chalcogenide NCs, typically truncated nanocubes, attach mainly via (100) facets.

Purpose of the Study:

• To demonstrate that existing NC superlattices are substructures of a simple cubic lattice.
• To explore novel 1D and 2D superlattices derived from this cubic system.
• To introduce a "LEGO® brick" concept for superlattice synthesis and electronic structure calculations.

Main Methods:

• Conceptualizing NC superlattices as building blocks within a cubic lattice framework.
• Investigating superlattices formed by different crystallographic orientations of cubic substructures.
• Developing analytical Hamiltonians based on the LEGO® brick model for electronic band structure calculations.

Main Results:

• All reported NC superlattices can be described as substructures of a simple cubic lattice.
• A variety of 1D and 2D superlattices can be synthesized by rearranging these cubic building blocks.
• The LEGO® brick approach yields analytical Hamiltonians with electronic band structures closely matching atomistic tight-binding calculations.

Conclusions:

• The LEGO® brick analogy provides a unified framework for understanding and synthesizing diverse NC superlattices.
• This concept simplifies the calculation of electronic band structures, facilitating the study of optoelectronic properties.
• The LEGO® approach offers a powerful tool for both the directed synthesis of superlattices and the theoretical analysis of their properties.