文章基本信息

标题：Moiré excitons in defective van der Waals heterostructures
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作者：Hongli Guo ; Xu Zhang ; Gang Lu 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2021
卷号：118
期号：32
DOI：10.1073/pnas.2105468118
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance Defects are inevitable in van der Waals (vdW) materials, but their role on moiré excitons remains unknown. While both moiré and defect potentials can trap excitons in twisted vdW heterostructures, their interplay has not been explored thus far. In this work, we perform first-principles simulations to elucidate the interplay of the defect and moiré potentials in tailoring the excitonic properties in twisted vdW heterostructures. Our work provides an in-depth study of defect-trapped moiré excitons in vdW heterostructures and establishes defect engineering as a promising strategy to tailor optoelectronic responses on demand. Excitons can be trapped by moiré potentials in van der Waals (vdW) heterostructures, forming ordered arrays of quantum dots. Excitons can also be trapped by defect potentials as single photon emitters. While the moiré and defect potentials in vdW heterostructures have been studied separately, their interplay remains largely unexplored. Here, we perform first-principles calculations to elucidate the interplay of the two potentials in determining the optoelectronic properties of twisted MoS 2/WS 2 heterobilayers. The binding energy, charge density, localization, and hybridization of the moiré excitons can be modulated by the competition and cooperation of the two potentials. Their interplay can also be tuned by vertical electric fields, which can either de-trap the excitons or strongly localize them. One can further tailor the interplay of the two potentials via defect engineering to create one-dimensional exciton lattices with tunable orientations. Our work establishes defect engineering as a promising strategy to realize on-demand optoelectronic responses.
关键词：enmoiré excitons;vdW heterostructures;defect engineering;TDDFT