Tuning ultrafast photocarrier dynamics of monolayer MoSe₂ by hole doping from MoO₃

In semiconductors, charge doping enables control over electrical and optical properties. The atomic thinness of two-dimensional (2D) semiconductors allows an effective doping strategy by interfacing them with other materials as donor or accepter. Heterostructures with type-III band alignment are particularly interesting, as ground-state charge transfer across the interface can dope both layers with desired type and concentration. Here, we demonstrate tuning of the photocarrier lifetime in monolayer MoSe₂ by forming a heterostructure with MoO₃. Monolayer MoSe₂ flakes were mechanically exfoliated and transferred onto bulk MoO₃ substrates using a dry transfer method. Photocarriers in MoSe₂ were excited and probed using photoluminescence and transient absorption spectroscopy with the probe tuned near its A-exciton resonance. By systematic comparison with MoSe₂ monolayers on hBN substrates, we reveal how MoO₃-induced doping alters photocarrier dynamics in MoSe₂. This effect offers a pathway to tailoring exciton lifetimes and charge transfer processes for optoelectronic and photonic applications based on 2D semiconductors.