Ultrafast Electronic Relaxation Dynamics of Atomically Thin MoS2 Is Accelerated by Wrinkling.
Ultrafast Electronic Relaxation Dynamics of Atomically Thin MoS2 Is Accelerated by Wrinkling.
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DOI：
10.1021/acsnano.3c02917
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发表时间：
2023-08
期刊：
影响因子：
17.1
通讯作者：
Ce Xu;Guoqing Zhou;E. Alexeev;A. Cadore;I. Paradisanos;A. Ott;G. Soavi;S. Tongay;G. Cerullo-G.-Cerul
中科院分区：
文献类型：
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作者：
Ce Xu;Guoqing Zhou;E. Alexeev;A. Cadore;I. Paradisanos;A. Ott;G. Soavi;S. Tongay;G. Cerullo-G.-Cerul
应变工程是一种很有吸引力的方法来调整过渡金属二硫属化物（TMD）的局部光电性能。虽然应变已被证明会影响TMD的纳秒载流子复合动力学，但其对亚皮秒电子弛豫动力学的影响仍未被探索。在这里，我们采用时间分辨光电子显微镜（TR-PEEM）和非绝热从头算分子动力学（NAMD）的组合，研究超快动力学的褶皱多层（ML）二硫化钼包括17层。在2.41 eV光激发后，在Γ谷处发生电子弛豫，对于褶皱ML-MoS2，时间常数为97 ± 2 fs，对于平坦ML-MoS2，时间常数为120 ± 2 fs。NAMD表明，退火允许较大幅度的MoS2层的运动，放松电子-声子耦合选择规则，扰动化学键，并增加电子态密度。因此，非绝热耦合增长和电子弛豫变得更快相比，平坦的ML-MoS2。我们的研究表明，亚皮秒电子弛豫动力学的TMD是服从应变工程和应用需要长寿命的热载流子，如热电子驱动的光捕获和反射，应采用无磨损的TMD。
Strain engineering is an attractive approach for tuning the local optoelectronic properties of transition metal dichalcogenides (TMDs). While strain has been shown to affect the nanosecond carrier recombination dynamics of TMDs, its influence on the sub-picosecond electronic relaxation dynamics is still unexplored. Here, we employ a combination of time-resolved photoemission electron microscopy (TR-PEEM) and nonadiabatic ab initio molecular dynamics (NAMD) to investigate the ultrafast dynamics of wrinkled multilayer (ML) MoS2 comprising 17 layers. Following 2.41 eV photoexcitation, electronic relaxation at the Γ valley occurs with a time constant of 97 ± 2 fs for wrinkled ML-MoS2 and 120 ± 2 fs for flat ML-MoS2. NAMD shows that wrinkling permits larger amplitude motions of MoS2 layers, relaxes electron-phonon coupling selection rules, perturbs chemical bonding, and increases the electronic density of states. As a result, the nonadiabatic coupling grows and electronic relaxation becomes faster compared to flat ML-MoS2. Our study suggests that the sub-picosecond electronic relaxation dynamics of TMDs is amenable to strain engineering and that applications which require long-lived hot carriers, such as hot-electron-driven light harvesting and photocatalysis, should employ wrinkle-free TMDs.