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Title: Self-assembled multi-layer simple cubic photonic crystals of oppositely charged colloids in confinement
Authors: Sankaewtong, Krongtum
Lei, Qun-li
Ni, Ran
Keywords: Engineering::Chemical engineering
Issue Date: 2019
Source: Sankaewtong, K., Lei, Q. & Ni, R. (2019). Self-assembled multi-layer simple cubic photonic crystals of oppositely charged colloids in confinement. Soft Matter, 15(15), 3104-3110.
Project: M4081781.120
Journal: Soft Matter
Abstract: Designing and fabricating self-assembled open colloidal crystals have become one major direction in the soft matter community because of many promising applications associated with open colloidal crystals. However, most of the self-assembled crystals found in experiments are not open but close-packed. Here, by using computer simulation, we systematically investigate the self-assembly of oppositely charged colloidal hard spheres confined between two parallel hard walls, and we find that the confinement can stabilize multi-layer NaCl-like (simple cubic) open crystals. The maximal number of layers of stable NaCl-like crystals increases with decreasing inverse screening length. More interestingly, at finite low temperature, the large vibrational entropy can stabilize some multi-layer NaCl-like crystals against the most energetically favoured close-packed crystals. In the parameter range studied, we find up to 4-layer NaCl-like crystals to be stable in confinement. Our photonic calculation shows that the inverse 4-layer NaCl-like crystal can already reproduce the large photonic band gaps of the bulk simple cubic crystal, which open in the low frequency range with a low dielectric contrast. This suggests new possibilities of using confined colloidal systems to fabricate open crystalline materials with novel photonic properties.
ISSN: 1744-683X
DOI: 10.1039/c9sm00018f
Rights: © 2019 Royal Society of Chemistry. All rights reserved.
Fulltext Permission: none
Fulltext Availability: No Fulltext
Appears in Collections:SCBE Journal Articles

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