Evidence for Fast Interlayer Energy Transfer in MoSe2/WS2 Heterostructures
Evidence for Fast Interlayer Energy Transfer in MoSe2/WS2 Heterostructures
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DOI：
10.1021/acs.nanolett.6b00801
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发表时间：
2016-07-01
期刊：
影响因子：
10.8
通讯作者：
Eda, Goki
中科院分区：
文献类型：
--
作者：
Kozawa, Daichi;Carvalho, Alexandra;Eda, Goki
限制在二维（2D）半导体中的强束缚激子是具有完美面内取向的偶极。在半导体2D晶体的垂直堆叠中，由于强的层间库仑相互作用，预期这种面内激子偶极子有效地耦合穿过货车德瓦尔斯能隙并交换它们的能量。然而，先前对第6族过渡金属二硫属化合物（TMD）异质双分子层的研究发现，激子衰减动力学是由层间电荷转移（CT）过程所主导的。在这里，我们报告的实验观察到的快速层间能量转移（ET）在MoSe 2/WS 2异质结构的光致发光激发（PLE）光谱。的转移速率的温度依赖性表明，ET是福斯特型涉及激子在WS 2层共振激发高阶激子在MoSe 2层。估计ET时间的顺序为1 ps是最快的相比，其他纳米结构的混合系统，如碳纳米管束。这些系统中的高效ET通过智能层工程为光放大和能量收集提供了前景。
Strongly bound excitons confined in two-dimensional (2D) semiconductors are dipoles with a perfect in-plane orientation. In a vertical stack of semiconducting 2D crystals, such in-plane excitonic dipoles are expected to efficiently couple across van der Waals gap due to strong interlayer Coulomb interaction and exchange their energy. However, previous studies on heterobilayers of group 6 transition metal dichalcogenides (TMDs) found that the exciton decay dynamics is dominated by interlayer charge transfer (CT) processes. Here, we report an experimental observation of fast interlayer energy transfer (ET) in MoSe2/WS2 heterostructures using photoluminescence excitation (PLE) spectroscopy. The temperature dependence of the transfer rates suggests that the ET is Forster-type involving excitons in the WS2 layer resonantly exciting higher order excitons in the MoSe2 layer. The estimated ET time of the order of 1 ps is among the fastest compared to those reported for other nanostructure hybrid systems such as carbon nanotube bundles. Efficient ET in these systems offers prospects for optical amplification and energy harvesting through intelligent layer engineering.