Moiré superlattices in van der Waals heterostructures have emerged as a powerful tool for engineering quantum phenomena. Here we report the observation of a correlated interlayer exciton insulator in a double-layer heterostructure composed of a WSe₂ monolayer and a WS₂/WSe₂ moiré bilayer that are separated by ultrathin hexagonal boron nitride. The moiré WS₂/WSe₂ bilayer features a Mott insulator state when the density of holes is one per moiré lattice site. When electrons are added to the Mott insulator in the WS₂/WSe₂ moiré bilayer and an equal number of holes are injected into the WSe₂ monolayer, a new interlayer exciton insulator emerges with the holes in the WSe₂ monolayer and the electrons in the doped Mott insulator bound together through interlayer Coulomb interactions. The interlayer exciton insulator is stable up to a critical hole density in the WSe₂ monolayer, beyond which the interlayer exciton dissociates. Our study highlights the opportunities for realizing quantum phases in double-layer moiré systems due to the interplay between the moiré flat band and strong interlayer electron interactions.

范德华异质结构中的莫尔超晶格已成为工程量子现象的有力工具。在这里，我们报告了在由超薄六方氮化硼隔开的 WSe ₂单层和 WS ₂ /WSe ₂莫尔双层组成的双层异质结构中的相关层间激子绝缘体的观察。当孔的密度为每个莫尔晶格位置一个时，莫尔 WS ₂ /WSe ₂双层具有莫特绝缘体状态。当电子被添加到 WS ₂ /WSe ₂莫尔双层中的莫特绝缘体中并且相同数量的空穴被注入到 WSe _2中时单层，新的层间激子绝缘体出现，WSe ₂单层中的空穴和掺杂莫特绝缘体中的电子通过层间库仑相互作用结合在一起。在WSe ₂单层中，层间激子绝缘体在达到临界空穴密度时是稳定的，超过该临界空穴密度，层间激子就会解离。我们的研究强调了由于莫尔平带和强层间电子相互作用之间的相互作用，在双层莫尔系统中实现量子相的机会。