Ultrafast charge transfer in atomically thin MoS2/WS2 heterostructures
Ultrafast charge transfer in atomically thin MoS2/WS2 heterostructures
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DOI：
10.1038/nnano.2014.167
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发表时间：
2014-09-01
影响因子：
38.3
通讯作者：
Wang, Feng
中科院分区：
文献类型：
--
作者：
Hong, Xiaoping;Kim, Jonghwan;Wang, Feng
最近，货车范德华异质结构作为一类新的材料出现，其中堆叠的原子级薄的二维层（包括石墨烯、六方氮化硼和过渡金属二硫属化物（MX 2））之间的量子耦合产生了迷人的新现象（1-10）。MX2异质结构对于新型光电和光伏应用特别令人兴奋，因为二维MX2单层可以在近红外到可见光谱范围内具有光学带隙，并表现出极强的光-物质相互作用（2，3，11）。理论预测，许多堆叠的MX2异质结构形成II型半导体异质结，其促进用于光检测和收集的有效电子-空穴分离（12-16）。在这里，我们报告的第一个实验观察超快的电荷转移在光激发的MoS 2/WS 2异质结构使用光致发光映射和飞秒泵浦探测光谱。我们发现，从二硫化钼层的WS 2层的空穴传输发生在50 fs光激发后，一个显着的速率为货车德瓦尔斯耦合的二维层。这种在货车范德华异质结构中的超快电荷转移可以实现用于光电子学和光捕获的新型二维器件。
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(1-10). 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(2,3,11). Theory predicts that many stacked MX2 heterostructures form type II semiconductor heterojunctions that facilitate efficient electron-hole separation for light detection and harvesting(12-16). 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.