Revealing exciton transport in atomically thin semiconductors

Exciton transport is a fundamental process that underlies the functionality of semiconductor optoelectronic devices. However, when excitons interact with one another, their transport pattern becomes unpredictable, posing a great challenge to harness their full potential in various applications. In our study, focusing on the exciton density change in a tungsten-disulfide monolayer, we observed that strong interactions between excitons can actually stop their movement. This finding contradicts the typical understanding of consistent exciton movement and reveals that a higher density might decrease the exciton-exciton annihilation rate due to reduced mobility. Our findings offer a valuable technique to examine exciton transport and deepen our grasp of their behavior in many-body interactions, which could pave the way for better-performing excitonic devices.