Evidence for Fast Interlayer Energy Transfer in MoSe2/WS2 Heterostructures

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• 作者：Daichi Kozawa ; Alexandra Carvalho ; Ivan Verzhbitskiy ; Francesco Giustiniano ; Yuhei Miyauchi ; Shinichiro Mouri ; A. H. Castro Neto ; Kazunari Matsuda ; Goki Eda
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：July 13, 2016
• 年：2016
• 卷：16
• 期：7
• 页码：4087-4093
• 全文大小：493K
• 年卷期：0
• ISSN：1530-6992

文摘

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 Förster-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.