Twisted transition metal dichalcogenide (TMD) bilayers exhibit periodic moiré potentials, which can trap excitons at certain high-symmetry sites. At small twist angles, TMD lattices undergo an atomic reconstruction, altering the moiré potential landscape via the formation of large domains, potentially separating the charges in-plane and leading to the formation of intralayer charge-transfer (CT) excitons. Here, we employ a microscopic, material-specific theory to investigate the intralayer charge-separation in atomically reconstructed MoSe₂–WSe₂ heterostructures. We identify three distinct and twist-angle-dependent exciton regimes including localized Wannier-like excitons, polarized excitons, and intralayer CT excitons. We calculate the moiré site hopping for these excitons and predict a fundamentally different twist-angle-dependence compared to regular Wannier excitons - presenting an experimentally accessible key signature for the emergence of intralayer CT excitons. Furthermore, we show that the charge separation and its impact on the hopping can be efficiently tuned via dielectric engineering.

中文翻译：

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范德华异质结构中莫尔激子的极化和电荷分离


扭曲的过渡金属二硫化物 （TMD） 双层表现出周期性莫尔电位，这可以在某些高对称位点捕获激子。在小扭曲角下，TMD 晶格经历原子重构，通过形成大畴来改变莫尔势景观，可能在平面内分离电荷并导致层内电荷转移 （CT） 激子的形成。在这里，我们采用微观的、材料特异性的理论来研究原子重构的 MoSe 2-WSe₂ 异质结构中的层内电荷分离。我们确定了三种不同的扭曲角依赖性激子机制，包括局部 Wannier 样激子、极化激子和层内 CT 激子。我们计算了这些激子的莫尔位点跳跃，并预测了与常规 Wannier 激子相比根本不同的扭曲角依赖性 - 为层内 CT 激子的出现提供了实验上可访问的键签名。此外，我们表明，电荷分离及其对跳跃的影响可以通过介电工程有效地调整。