Luo Ziyu, Zheng Weihao, Luo Nannan, Liu Bo, Zheng Biyuan, Yang Xing, Liang Delang, Qu Junyu, Liu Huawei, Chen Ying, Jiang Ying, Chen Shula, Zou Xiaolong, Pan Anlian
Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometriscs and College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082, China.
Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute and Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, Guangdong 518055, China.
Nano Lett. 2022 Mar 9;22(5):2112-2119. doi: 10.1021/acs.nanolett.2c00462. Epub 2022 Feb 28.
Transition metal dichalcogenide monolayers exhibit ultrahigh surface sensitivity since they expose all atoms to the surface and thereby influence their optoelectronic properties. Here, we report an intriguing lightening of the photoluminescence (PL) from the edge to the interior over time in the WS monolayers grown by physical vapor deposition method, with the whole monolayer brightened eventually. Comprehensive optical studies reveal that the PL enhancement arises from the p doping induced by oxygen adsorption. First-principles calculations unveil that the dissociation of chemisorbed oxygen molecule plays a significant role; i.e., the dissociation at one site can largely promote the dissociation at a nearby site, facilitating the photoluminescence lightening. In addition, we further manipulate such PL brightening rate by controlling the oxygen concentration and the temperature. The presented results uncover the extraordinary surface chemistry and related mechanism in WS monolayers, which deepens our insight into their unique PL evolution behavior.
过渡金属二硫属化物单层具有超高的表面灵敏度，因为它们将所有原子暴露于表面，从而影响其光电特性。在此，我们报告了通过物理气相沉积法生长的WS单层中，光致发光（PL）随时间从边缘到内部呈现出一种有趣的变亮现象，最终整个单层都会变亮。综合光学研究表明，PL增强源于氧吸附诱导的p型掺杂。第一性原理计算揭示，化学吸附氧分子的解离起着重要作用；即一个位点的解离能极大地促进附近位点的解离，从而促进光致发光变亮。此外，我们通过控制氧浓度和温度进一步调控这种PL变亮速率。所呈现的结果揭示了WS单层中非凡的表面化学及相关机制，加深了我们对其独特PL演化行为的理解。
