J Phys Chem Lett. 2023 Apr 13;14(14):3360-3367. doi: 10.1021/acs.jpclett.2c03856. Epub 2023 Mar 30.
Interfacial polarons determine the distribution of free charges at the interface and thus play important roles in manipulating the physicochemical properties of hybridized polaronic materials. In this work, we investigated the electronic structures at the atomically flat interface of the single-layer MoS (SL-MoS) on the rutile TiO surface using high-resolution angle-resolved photoemission spectroscopy. Our experiments directly visualized both the valence band maximum and the conduction band minimum (CBM) of SL-MoS at the K point, which clearly defines a direct bandgap of ∼2.0 eV. Detailed analyses corroborated by density functional theory calculations demonstrated that the CBM of MoS is formed by the trapped electrons at the MoS/TiO interface that couple with the longitudinal optical phonons in the TiO substrate through an interfacial Fröhlich polaron state. Such an interfacial coupling effect may register a new route for tuning the free charges in the hybridized systems of two-dimensional materials and functional metal oxides.
界面极化子决定了界面处自由电荷的分布，因此在操纵杂化极化子材料的物理化学性质方面发挥着重要作用。在这项工作中，我们使用高分辨率角分辨光发射谱研究了单晶二硫化钼（SL-MoS）在金红石 TiO 表面的原子平坦界面处的电子结构。我们的实验直接观察到了 K 点处 SL-MoS 的价带最大值和导带最小值（CBM），这明确定义了一个约为 2.0 eV 的直接带隙。由密度泛函理论计算证实的详细分析表明，MoS 的 CBM 是由 MoS/TiO 界面处的被俘获电子形成的，这些电子通过界面 Frohlich 极化子态与 TiO 衬底中的纵光学声子耦合。这种界面耦合效应可能为调节二维材料和功能金属氧化物杂化体系中的自由电荷提供了一条新途径。
