Thickness-Dependent Interlayer Charge Transfer in MoSe2/MoS2 Heterostructures Studied by Femtosecond Transient Absorption Measurements,ACS Applied Materials & Interfaces

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Thickness-Dependent Interlayer Charge Transfer in MoSe2/MoS2 Heterostructures Studied by Femtosecond Transient Absorption Measurements
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2021-01-31 , DOI: 10.1021/acsami.0c18268
Ting Zheng _{1,

2} , Pavel Valencia-Acuna ₂ , Peymon Zereshki ₂ , Katherine M. Beech ₂ , Lier Deng ₂ , Zhenhua Ni ₁ , Hui Zhao ₂

Affiliation

We report observations of a strong thickness dependence for charge transfer (CT) from MoSe₂ to MoS₂, as evidenced by transient absorption measurements. By time-resolving CT from MoSe₂ monolayers (1Ls) to MoS₂ flakes of varying thicknesses, including 1L, bilayer (2L), and trilayer (3L), we find that the CT time is several picoseconds in the 1L-MoSe₂/3L-MoS₂ heterostructure, which is much longer than that of 1L-MoSe₂/1L-MoS₂ and 1L-MoSe₂/2L-MoS₂ heterostructures. In addition, the recombination lifetime of the interlayer excitons in the 1L/3L heterostructure is several times longer than that of 1L/1L and 1L/2L heterostructures, reaching 800 ps. Furthermore, we show that a prepulse can reduce the CT time and enhance the interlayer exciton recombination in the 1L/3L heterostructure. These findings illustrate that layer thickness can be an important parameter to control the CT property of van der Waals heterostructures. These experimental results also provide important information for further refining the understanding of the physical mechanisms of CT in van der Waals heterostructures.

中文翻译：

飞秒瞬态吸收测量研究MoSe ₂ / MoS ₂异质结构中与厚度有关的层间电荷转移

我们报告了从MoSe ₂到MoS _2的电荷转移（CT）的强烈厚度依赖性的观察结果，这由瞬态吸收测量法证明。通过从MoSe ₂单层（1Ls）到不同厚度的MoS ₂薄片（包括1L，双层（2L）和三层（3L））的CT时间分辨，我们发现CT时间在1L-MoSe ₂ /中为几皮秒。3L-MoS ₂异质结构，比1L-MoSe ₂ / 1L-MoS ₂和1L-MoSe ₂ / 2L-MoS ₂更长异质结构。此外，层间激子在1L / 3L异质结构中的复合寿命比1L / 1L和1L / 2L异质结构的复合寿命长几倍，达到800 ps。此外，我们表明，预脉冲可以减少CT时间并增强1L / 3L异质结构中的层间激子复合。这些发现说明，层厚度可以是控制范德华力异质结构CT性能的重要参数。这些实验结果也为进一步完善对范德华异质结构中CT物理机理的理解提供了重要信息。

更新日期：2021-02-10

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