Charge-transfer (CT) excitons at heterointerfaces play a critical role in light to electricity conversion using organic and nanostructured materials. However, how CT excitons migrate at these interfaces is poorly understood. We investigate the formation and transport of CT excitons in two-dimensional WS₂/tetracene van der Waals heterostructures. Electron and hole transfer occurs on the time scale of a few picoseconds, and emission of interlayer CT excitons with a binding energy of ~0.3 eV has been observed. Transport of the CT excitons is directly measured by transient absorption microscopy, revealing coexistence of delocalized and localized states. Trapping-detrapping dynamics between the delocalized and localized states leads to stretched-exponential photoluminescence decay with an average lifetime of ~2 ns. The delocalized CT excitons are remarkably mobile with a diffusion constant of ~1 cm² s^-1. These highly mobile CT excitons could have important implications in achieving efficient charge separation.

中文翻译：

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二维WS2 /并四苯异质结构中的高度可移动电荷转移激子。

异质界面上的电荷转移（CT）激子在使用有机和纳米结构材料进行光到电的转换中起着至关重要的作用。但是，人们对CT激子如何在这些界面上迁移的了解却很少。我们研究二维WS ₂中CT激子的形成和运输/并四苯范德华结构。电子和空穴的转移发生在几皮秒的时间范围内，并且观察到结合能为〜0.3 eV的层间CT激子的发射。CT激子的转运是通过瞬态吸收显微镜直接测量的，揭示了离域和局部状态的共存。局域化状态和局域化状态之间的陷获-陷获动力学导致拉伸指数光致发光衰减，平均寿命为〜2 ns。离域的CT激子以〜1 cm ² s ^-1的扩散常数显着移动。这些高度移动的CT激子可能对实现有效的电荷分离具有重要意义。