Interlayer exciton transition in van der Waals heterostructure modulated by located vertical electric field

Interlayer exciton-trion interconversion is central to two-dimensional excitonics, while electrically modulating the exciton interconversion in van der Waals heterostructures remains underexplored yet. Herein, we report a systematic investigation of interlayer many-body dynamics in a WS₂/MoS₂ van der Waals heterostructure subjected to a micrometer-scale vertical electric field generated by an atomic-force-microscope probe. By synergizing hyperspectral photoluminescence mapping with density-functional calculations, the abrupt and reversible switching of the trion/exciton intensity ratio has been observed at two critical biases (-0.054 and +0.076 V Å^-1), which coincide with a type-II to type-I band-alignment crossover and a direct-to-indirect gap transition, respectively. The quantitative agreement between experimental values and mass-action theory across the entire electric field window demonstrates that a local vertical field affords spatially selective, continuous, and non-volatile control over interlayer exciton conversion, establishing a route toward reconfigurable 2D excitonics and field-programmable quantum emitters.