Self-Assembled Chiral Photonic Crystals from a Colloidal Helix Racemate
Self-Assembled Chiral Photonic Crystals from a Colloidal Helix Racemate
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来自胶体螺旋外消旋体的自组装手性光子晶体
DOI：
10.1021/acsnano.8b02116
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发表时间：
2018-07-01
期刊：
影响因子：
17.1
通讯作者：
Ma, Yu-qiang
中科院分区：
文献类型：
--
作者：
Lei, Qun-li;Ni, Ran;Ma, Yu-qiang
由微螺旋组成的手性晶体具有许多光学性质，但现有的制造工艺限制了它们在光子器件中的大规模应用。在这里，我们使用一种简化的模拟方法，研究了一种自下而上的自组装路线，从胶体螺旋外消旋体的近晶单层构建螺旋晶体。随着密度的增加，体系发生熵驱动的共结晶，形成不同对称度、不同螺旋形状的晶体。特别地，我们确定了两种排列在二元蜂窝和方形晶格中的螺旋晶体，它们本质上是由两组对手性晶体组成的。光子计算表明，这些手性结构具有较大的完整光子带隙。此外，在自组装的手性方形晶体中，我们还发现双极化带隙选择性地禁止特定手性的圆偏振光沿螺旋轴方向传播。我们提出的系统中的自组装过程是鲁棒的，这表明使用手性胶体组装光子超材料的可能性。
Chiral crystals consisting of microhelices have many optical properties, while presently available fabrication processes limit their large-scale applications in photonic devices. Here, by using a simplified simulation method, we investigate a bottom-up self-assembly route to build up helical crystals from the smectic monolayer of a colloidal helix racemate. With increasing the density, the system undergoes an entropy-driven cocrystallization by forming crystals of various symmetries with different helical shapes. In particular, we identify two crystals of helices arranged in binary honeycomb and square lattices, which are essentially composed of two sets of opposite-handed chiral crystals. Photonic calculations show that these chiral structures can have large complete photonic band gaps. In addition, in the self assembled chiral square crystal, we also find dual polarization band gaps that selectively forbid the propagation of circularly polarized light of a specific handedness along the helical axis direction. The self-assembly process in our proposed system is robust, suggesting possibilities of using chiral colloids to assemble photonic metamaterials.