Bright monolayer tungsten disulfide via exciton and trion chemical modulations
Bright monolayer tungsten disulfide via exciton and trion chemical modulations
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通过激子和三重子化学调制获得明亮的单层二硫化钨
DOI：
10.1039/c7nr09442f
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发表时间：
2018
期刊：
影响因子：
6.7
通讯作者：
Qi Jie Wang
中科院分区：
文献类型：
--
作者：
Ye Tao;Xuechao Yu;Jiewei Li;Houkun Liang;Ying Zhang;Wei Huang;Qi Jie Wang
原子薄的过渡金属二硫族化合物（TMDCs）具有优异的电学和光学性能，在光电探测器、晶体管、发光器件等新型光电应用中引起了人们的广泛关注。然而，中性激子与电子结合形成的束缚电子显著降低了TMDCs的光致发光效率。在这项研究中，我们报告了一种简单而有效的化学掺杂策略来调制单层二硫化钨（WS2）的光学性质。作为一个示范性的例子，化学掺杂的WS2单层显示出显著的PL增强，比原始WS2高出约一个数量级。这种突出的PL增强归因于这样一个事实，即通过从WS2到化学掺杂剂的电荷转移，促进电子束缚的形成的多余电子的数量减少了。此外，在化学掺杂的WS2单层中，也观察到圆极化度从~ 9.0%提高到~ 41.5%。这项工作描述了一种可行的策略，通过激子调制来操纵TMDCs的光学特性，使TMDCs有希望成为多功能半导体光子器件的候选者。
Atomically thin transition metal dichalcogenides (TMDCs) with exceptional electrical and optical properties have drawn tremendous attention for use in novel optoelectronic applications as photodetectors, transistors, light emitters, etc. However, electron bound trions formed through the combination of neutral excitons and electrons significantly decrease the photoluminescence (PL) efficiency of TMDCs. In this study, we report a simple yet efficient chemical doping strategy to modulate the optical properties of monolayer tungsten disulfide (WS2). As a demonstrative example, a chemically doped monolayer of WS2 exhibits remarkable PL enhancement of about one order of magnitude higher than that of pristine WS2. This outstanding PL enhancement is attributed to the fact that excess electrons, which promote the formation of electron-bound trions, are reduced in number through charge transfer from WS2 to the chemical dopant. Furthermore, an improved degree of circular polarization from ∼9.0% to ∼41.5% was also observed in the chemically doped WS2 monolayer. This work describes a feasible strategy to manipulate the optical properties of TMDCs via exciton modulation, making TMDCs promising candidates for versatile semiconductor-based photonic devices.