Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA.
Institute for Advanced Technologies, Shahid Rajaee Teacher Training University, 16875-163, Lavizan, Tehran, Iran and Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
Nanoscale. 2017 Mar 23;9(12):4205-4218. doi: 10.1039/c6nr08586e.
Inspired by recent experiments, the trapping of molecules in 2D materials has gained increasing attention due to the unique ability of the molecules to modulate the electronic and optical properties of 2D materials, which calls for fundamental understanding and predictive design strategies. Herein, we focus on mono- and double-layer graphene encapsulating various MgO clusters and explore their diverse electronic and optical properties using a number of high-level first-principles calculations. By correlating the stability of adsorption, geometry, charge transfer, band structures, optical absorption spectrum, and the van der Waals pressure, our results decode various synergies in electro- and opto-mutable properties of MgO/graphene systems. We found that 2D-MgO flakes on graphene layers exhibit surface polarization effects - in contrast to their isolated neutral flakes - and show a significant charge transfer from graphene to n-doped flakes, breaking the symmetry of graphene layers. We obtained a van der Waals pressure of ∼0.7 (0.9) GPa on bilayer graphene encapsulating MgO nanoclusters, which matches extremely well with experiment. While there is one quantum emission in the visible light region for a single MgO flake, a wide range of visible light is accessible for MgO on mono- and double-layer graphene. Overall, these findings provide new physical insights and design strategies to modulate 2D materials with several applications in optoelectronics while significantly broadening the spectrum of strategies for fabricating new hybrid 2D heterostructures by encapsulating external molecules.
受近期实验的启发，由于分子具有调节二维材料电子和光学性质的独特能力，因此在二维材料中捕获分子引起了越来越多的关注，这需要对其进行深入的理解和预测性设计策略。本文中，我们专注于单层和双层石墨烯封装各种 MgO 团簇，并使用多种高精度第一性原理计算来研究它们的各种电子和光学性质。通过关联吸附稳定性、几何形状、电荷转移、能带结构、光吸收谱和范德华压力，我们的结果解码了 MgO/石墨烯体系中电和光可调性质的各种协同作用。我们发现，二维 MgO 薄片在石墨烯层上表现出表面极化效应——与孤立的中性薄片相反——并显示出从石墨烯到 n 型掺杂薄片的显著电荷转移，打破了石墨烯层的对称性。我们在双层石墨烯封装 MgO 纳米团簇上获得了约 0.7（0.9）GPa 的范德华压力，这与实验非常吻合。虽然单个 MgO 薄片在可见光区域有一个量子发射，但 MgO 在单层和双层石墨烯上的可见光范围很广。总的来说，这些发现为调制二维材料提供了新的物理见解和设计策略，在光电领域有多种应用，同时通过封装外部分子显著拓宽了制造新型二维杂化异质结构的策略范围。
