Engineering Substrate Interactions for High Luminescence Efficiency of Transition-Metal Dichalcogenide Monolayers

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• 作者：Yifei Yu ; Yiling Yu ; Chao Xu ; Yong-Qing Cai ; Liqin Su ; Yong Zhang ; Yong-Wei Zhang ; Kenan Gundogdu and Linyou Cao
• 刊名：Advanced Functional Materials
• 出版年：2016
• 出版时间：July 12, 2016
• 年：2016
• 卷：26
• 期：26
• 页码：4733-4739
• 全文大小：1141K
• ISSN：1616-3028

文摘

It is demonstrated that the luminescence efficiency of monolayers composed of MoS₂, WS₂, and WSe₂ is significantly limited by the substrate and can be improved by orders of magnitude through substrate engineering. The substrate affects the efficiency mainly through doping the monolayers and facilitating defect-assisted nonradiative exciton recombinations, while the other substrate effects including straining and dielectric screening play minor roles. The doping may come from the substrate and substrate-borne water moisture, the latter of which is much stronger than the former for MoS₂ and WS₂ but negligible for WSe₂. Using proper substrates such as mica or hexagonal boron nitride can substantially mitigate the doping effect. The defect-assisted recombination depends on the interaction between the defect in the monolayer and the substrate. Suspended monolayers, in which the substrate effects are eliminated, may have efficiency up to 40% at room temperatures. The result provides useful guidance for the rational design of atomic-scale light emission devices.