External field regulation strategies for exciton dynamics in 2D TMDs

Two-dimensional (2D) transition metal chalcogenides (TMDs) are regarded as promising materials for micro-optoelectronic devices and next-generation logic devices due to their novel optoelectronic properties, such as strong excitonic effects, tunable direct bandgap from visible to near-infrared regions, valley pseudospin degree of freedom, and so on. Recently, triggered by the growing demand to optimize the performance of TMDs devices, external field regulation engineering has attracted great attention. The goal of this operation is to exploit the external fields to control exciton dynamics in 2D TMDs, including exciton formation and relaxation, and to finally achieve high-performance 2D TMDs devices. Although the regulation strategies of exciton dynamics in 2D TMDs have been well explored, the underlying mechanisms of different regulation strategies need to be further understood due to the complex many-body interactions in exciton dynamics. Here, we first give a brief summary of the fundamental processes of exciton dynamics in 2D TMDs and then summarize the main field-regulation strategies. Particular emphasis is placed on discussing the underlying mechanisms of how different field-regulation strategies control varied fundamental processes. A deep understanding of field regulation provides direct guidelines for the integrated design of 2D TMDs devices in the future.