Guo Chunhao, Xu Junqing, Ping Yuan
Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, 95064, United States of America.
J Phys Condens Matter. 2021 May 11;33(23). doi: 10.1088/1361-648X/abeacf.
Substrates have strong effects on optoelectronic properties of two-dimensional (2D) materials, which have emerged as promising platforms for exotic physical phenomena and outstanding applications. To reliably interpret experimental results and predict such effects at 2D interfaces, theoretical methods accurately describing electron correlation and electron-hole interaction such as first-principles many-body perturbation theory are necessary. In our previous work (2020205113), we developed the reciprocal-space linear interpolation method that can take into account the effects of substrate screening for arbitrarily lattice-mismatched interfaces at the GW level of approximation. In this work, we apply this method to examine the substrate effect on excitonic excitation and recombination of 2D materials by solving the Bethe-Salpeter equation. We predict the nonrigid shift of 1s and 2s excitonic peaks due to substrate screening, in excellent agreements with experiments. We then reveal its underlying physical mechanism through 2D hydrogen model and the linear relation between quasiparticle gaps and exciton binding energies when varying the substrate screening. At the end, we calculate the exciton radiative lifetime of monolayer hexagonal boron nitride with various substrates at zero and room temperature, as well as the one of WSwhere we obtain good agreement with experimental lifetime. Our work answers important questions of substrate effects on excitonic properties of 2D interfaces.
衬底对二维（2D）材料的光电特性有很强的影响，二维材料已成为奇异物理现象和卓越应用的有前景的平台。为了可靠地解释实验结果并预测二维界面处的此类效应，需要诸如第一性原理多体微扰理论等能准确描述电子关联和电子-空穴相互作用的理论方法。在我们之前的工作（2020205113）中，我们开发了倒易空间线性插值方法，该方法可以在GW近似水平上考虑任意晶格失配界面的衬底屏蔽效应。在这项工作中，我们应用此方法通过求解贝叶斯 - 萨尔皮特方程来研究衬底对二维材料激子激发和复合的影响。我们预测了由于衬底屏蔽导致的1s和2s激子峰的非刚性位移，与实验结果高度吻合。然后，我们通过二维氢模型以及改变衬底屏蔽时准粒子能隙与激子结合能之间的线性关系揭示了其潜在的物理机制。最后，我们计算了零温和室温下具有各种衬底的单层六方氮化硼的激子辐射寿命，以及WS的激子辐射寿命，我们得到的结果与实验寿命吻合良好。我们的工作回答了衬底对二维界面激子特性影响的重要问题。
