Exciton Dynamics and Optoelectronic Responses in Monolayer MoSe ₂ under Low in-Plane Electric Fields

Exciton dynamics in two-dimensional materials critically determine both their luminescent and electrical responses in optoelectronic devices. Despite the central role of in-plane electric fields in device operation, their influence on exciton dynamics remains underexplored. Here, we systematically investigate how low in-plane electric fields modulate exciton dynamics in monolayer MoSe 2 and how these microscopic processes manifest in photocurrent and photoluminescence (PL). Using simultaneous photocurrent detection and spectroscopic measurements we reveal that in-plane fields promote exciton formation, enhancing PL while increasing the population of dissociated excitons. Transient absorption (TA) at varying excitation energies shows that although ground-state excitons are only weakly perturbed by low in-plane fields, the field strongly enhances exciton-free carrier scattering and suppresses exciton–exciton annihilation, thereby significantly affecting the exciton decay dynamics. Our results demonstrate that controlling exciton–carrier interactions via in-plane fields provides a versatile strategy for simultaneously improving photon-to-electron conversion and radiative efficiency, offering new avenues for the design of high-performance multifunctional optoelectronic devices.