Self-Assembly of Colloidal Diamond and Related Lattices for 3-D Photonic Band Gap Materials
Abstract
Major Goals: The major overarching goal of this project was to develop a method using colloidal self-assembly to fabricate photonic crystals that exhibit a full omnidirectional 3D photonic band gap (PBG) at optical and near-infrared frequencies. As originally conceived and proposed, we planned to do this by self-assembling a colloidal superlattice isomorphic to the metallic compound MgCu2, which is one of several so-called Laves phases and consists of two sublattices, one cubic diamond, and the other pyrochlore. The idea was to self-assemble this structure and then selectively remove the (sacrificial) pyrochlore sublattice leaving only the diamond sublattice, which would be used as a template for making an inverse diamond photonic crystal. However, as we made progress toward this goal, we developed a new method by which we could directly self-assemble a cubic diamond lattice from colloidal particles without the need for a sacrificial sublattice. The new method eliminated the need to remove the pyrochlore sublattice, which made it simpler and more robust than the original method. Thus, while the overall goal of the project did not change, the means by which we planned to achieve our goals shifted to this new more direct self-assembly route. Last year (2020), we published a demonstration of our new method to directly self-assemble a stand-alone colloidal crystal with a cubic diamond crystal structure. This appeared in the journal Nature in October 2020. The self-assembly of colloidal diamond had not been done previously. This represented a major breakthrough as the diamond lattice is generally considered to be the best crystalline lattice for making a material with a full photonic band gap (PBG). The diamond lattice as assembled from the polymer colloidal particles we employ does not have a photonic band gap as the dielectric contrast between the particles and the matrix (water or air) is not large enough to open up a band gap.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 17, 2021
- Accession Number
- AD1196579
Entities
People
- David J. Pine
Organizations
- New York University