The substrate effect is an important issue in the properties of two-dimensional transition metal dichalcogenides (2D TMDs). Quantitatively determining the dependence of the photoluminescence (PL) emission properties and the excitonic behavior of single-layer 2D materials in a specific dielectric environment would provide helpful guidance for the rational design of substrates for high performance 2D TMD PL emission devices. Here, using a WSe2 monolayer on different substrates as a model system, it is demonstrated that the PL emission intensities can drastically change depending on the substrate effect. From the analysis of the excitonic behavior, the results reveal that the spectral weight between the neutral and charged excitons in the PL spectra is significantly modified by the substrate types, and the weight factor is dependent on the laser excitation density. The charged exciton binding energy is obviously negatively related to the substrate dielectric constant. Furthermore, the change trends of the binding energy of the monolayer WSe2 on different substrates are basically the same for the increase of the excitation density. These results suggest that the choice of the substrate plays a significant role in the modulation of the PL properties and exciton states of atomically thin WSe2; hence, substrate engineering should be carefully considered in the design of future 2D devices.

中文翻译：

---

衬底对化学气相沉积转移单层 WSe2 光致发光的影响

底物效应是二维过渡金属二硫属元素化物 (2D TMD) 性能中的一个重要问题。定量确定特定介电环境中单层二维材料的光致发光 (PL) 发射特性和激子行为的依赖性将为高性能二维 TMD PL 发射器件的基板的合理设计提供有益的指导。在这里，使用不同基板上的 WSe2 单层作为模型系统，证明了 PL 发射强度可以根据基板效应发生剧烈变化。从激子行为的分析中，结果表明PL光谱中中性和带电激子之间的光谱权重被底物类型显着改变，权重因子取决于激光激发密度。带电激子结合能显然与衬底介电常数呈负相关。此外，随着激发密度的增加，不同衬底上单层WSe2结合能的变化趋势基本相同。这些结果表明，衬底的选择在原子级薄 WSe2 的 PL 特性和激子态的调制中起着重要作用。因此，在未来 2D 设备的设计中应仔细考虑基板工程。随着激发密度的增加，不同衬底上单层WSe2结合能的变化趋势基本相同。这些结果表明，衬底的选择在原子级薄 WSe2 的 PL 特性和激子态的调制中起着重要作用。因此，在未来 2D 设备的设计中应仔细考虑基板工程。随着激发密度的增加，不同衬底上单层WSe2结合能的变化趋势基本相同。这些结果表明，衬底的选择在原子级薄 WSe2 的 PL 特性和激子态的调制中起着重要作用。因此，在未来 2D 设备的设计中应仔细考虑基板工程。