Direct Visualization of Exciton Transport in Defective Few-Layer WS2 by Ultrafast Microscopy.,Advanced Materials

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Direct Visualization of Exciton Transport in Defective Few-Layer WS2 by Ultrafast Microscopy.
Advanced Materials ( IF 27.4 ) Pub Date : 2019-11-27 , DOI: 10.1002/adma.201906540
Huan Liu ₁ , Chong Wang ₁ , Zhengguang Zuo ₁ , Dameng Liu ₁ , Jianbin Luo ₁

Affiliation

As defects usually limit the exciton diffusion in 2D transition metal dichalcogenides (TMDCs), the interaction knowledge of defects and exciton transport is crucial for achieving efficient TMDC-based devices. A direct visualization of defect-modulated exciton transport is developed in few-layer WS2 by ultrafast transient absorption microscopy. Atomic-scale defects are introduced by argon plasma treatment and identified by aberration-corrected scanning transmission electron microscopy. Neutral excitons can be captured by defects to form bound excitons in 7.75-17.88 ps, which provide a nonradiative relaxation channel, leading to decreased exciton lifetime and diffusion coefficient. The exciton diffusion length of defective sample has a drastic reduction from 349.44 to 107.40 nm. These spatially and temporally resolved measurements reveal the interaction mechanism between defects and exciton transport dynamics in 2D TMDCs, giving a guideline for designing high-performance TMDC-based devices.

中文翻译：

通过超快速显微镜直接观察缺陷层很少的WS2中的激子转运。

由于缺陷通常会限制激子在2D过渡金属二硫化碳（TMDC）中的扩散，因此，缺陷与激子迁移的相互作用知识对于实现高效的基于TMDC的器件至关重要。通过超快速瞬态吸收显微镜，在几层WS2中开发了缺陷调节激子运输的直接可视化。原子级缺陷通过氩等离子体处理引入，并通过像差校正的扫描透射电子显微镜进行鉴定。中性激子可以被缺陷捕获，从而在7.75-17.88 ps的范围内形成束缚激子，从而提供非辐射弛豫通道，从而导致激子寿命和扩散系数降低。缺陷样品的激子扩散长度从349.44 nm急剧减小到107.40 nm。

更新日期：2020-01-15

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