Ultrafast charge transfer in atomically thin MoS₂/WS₂ heterostructures.
By Xiaoping Hong, Jonghwan Kim, Sufei Shi, Yu Zhang, Chenhao Jin, Yinghui Sun, S. Tongay, Junqiao Wu, Yanfeng Zhang, Feng Wang. Nature Nanotechnology, 2014
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Van der Waals heterostructures have recently emerged as a new class of materials, where quantum coupling between stacked atomically thin two-dimensional layers, including graphene, hexagonal-boron nitride and transition-metal dichalcogenides (MX2), give rise to fascinating new phenomena. MX2 heterostructures are particularly exciting for novel optoelectronic and photovoltaic applications, because two-dimensional MX2 monolayers can have an optical bandgap in the near-infrared to visible spectral range and exhibit extremely strong light-matter interactions. Theory predicts that many stacked MX2 heterostructures form type II semiconductor heterojunctions that facilitate efficient electron-hole separation for light detection and harvesting. Here, we report the first experimental observation of ultrafast charge transfer in photoexcited MoS2/WS2 heterostructures using both photoluminescence mapping and femtosecond pump-probe spectroscopy. We show that hole transfer from the MoS2 layer to the WS2 layer takes place within 50 fs after optical excitation, a remarkable rate for van der Waals coupled two-dimensional layers. Such ultrafast charge transfer in van der Waals heterostructures can enable novel two-dimensional devices for optoelectronics and light harvesting.
Subfields: Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/ea087bd648495782c60146bd0f1483d13b705a33
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