  Interlayer excitons (IXs) formed at the interface of atomically-thin
semiconductors possess various novel properties. In a parallel development,
nanoscale strain engineering has emerged as an effective means for creating 2D
quantum light sources. Exploring the intersection of these two exciting areas,
where strain and defects are exploited for the manipulation of IX toward the
emergence of new functionalities, is currently at a nascent stage. Here, using
MoS2/WSe2 heterostructure as a model system, we demonstrate how strain,
defects, and layering can be utilized to create defect-bound IXs capable of
bright, robust, and tunable quantum light emission in the technologically
important near-infrared spectral range. We were able to achieve ultra-high
single-photon purity with g(2)(0) = 0.01. Our strategy of creating
site-controlled QEs from the defect-bound IXs represents a paradigm shift in 2D
quantum photonics research, from engineering intralayer exciton in monolayer
structures towards IXs at the interface of 2D heterostructures.
