MoS₂/MnPS₃异质结界面电荷转移特性调制研究

Modulation of Charge Transfer Properties at the MoS₂/MnPS₃ Heterojunction Interface

摘要: 单层二维过渡金属二硫族化合物(2D-TMDCs)由于特殊的层状结构、丰富的激子种类等优异的物理性质被广泛应用于各种半导体器件的制备中。但单层2D-TMDCs由于其吸光性弱及内部激子复合率低等因素导致其在光探测器、发光器件中的表现不佳，限制了其在光电器件领域的发展。本工作将MnPS₃与单层二维材料MoS₂通过堆叠构成2D/2D异质结。具有明显的荧光增强现象，存在明显的界面电荷转移行为。实验结果显示随着激光功率的增大，异质结的发光峰位向短波数方向移动，主要归于温度升高，带隙收缩引起的发光峰红移。对异质结PL光谱进行洛伦兹拟合，随激光功率的增加，A⁻激子、A激子和B激子均逐渐红移，发光强度均增高。随着异质结中MnPS₃厚度的增加，B激子比重降低，A激子增加，A⁻激子先增加再降低，MnPS₃的厚度对异质结中的激子变化有重要的调制功能，导致其不同的发光特性。本研究中描述了2D/2D异质结的电荷转移行为和不同激子之间的动态竞争，在充分发挥各个组分的优势的情况下，对异质结构界面性质进行了多角度分析，未来可通过调节MnPS₃厚度及激光功率的手段精准调控异质结光电器件的性能，为实现高性能光电器件的制备奠定基础。

Abstract: Single-layer two-dimensional transition metal disulfide compounds (2D-TMDCs) are widely used in the preparation of various semiconductor devices due to their excellent physical properties such as special layered structure and abundant exciton species. However, the poor performance of monolayer 2D-TMDCs in photodetectors and light-emitting devices due to their weak light absorption and low internal exciton complexation rate has limited their development in the field of optoelectronic devices. In this work, MnPS₃ and single-layer two-dimensional material MoS₂ are stacked to form a 2D/2D heterojunction by stacking. There is an obvious fluorescence enhancement phenomenon and obvious interfacial charge transfer behavior. The experimental results show that the luminescence peak position of the heterojunction moves toward the short wavelength direction with the increase of laser power, which is mainly attributed to the red shift of the luminescence peak caused by the bandgap contraction with the increase of temperature. The Lorentzian fitting of the PL spectra of the heterojunction shows that the A⁻ exciton, A exciton, and B exciton are gradually red-shifted and the luminescence intensities are all increased with the increase of laser power. Furthermore, as the thickness of MnPS3 in the heterojunction increases, the proportion of B excitons decreases, A excitons increase, and A⁻ excitons first increase and then decrease, indicating that the thickness of MnPS₃ plays a crucial role in modulating the exciton dynamics within the heterojunction, leading to distinct luminescence characteristics. In this study, the charge transfer behavior of 2D/2D heterojunction and the dynamic competition between different excitons are described, and the interfacial properties of the heterostructure are analyzed from multiple perspectives while giving full play to the advantages of each component. In the future, the performance of the heterojunction optoelectronic device can be precisely tuned by means of adjusting the thickness of MnPS₃ and the laser power, which lays the foundation for the realization of high-performance optoelectronic device fabrication.