Abstract
A current obstacle to the development of extremely flexible and high‐performance optoelectronic devices using transition metal dichalcogenide nanosheets is the incomplete understanding of the exciton and free carrier recombination in the presence of defects. Here, taking liquid‐phase exfoliated few‐layer MoS2 nanosheets as a model system, we demonstrate the exciton and free carrier recombination mechanism by employing pump energy and fluence‐dependent ultrafast transient absorption spectroscopy. We demonstrate that 3.10 eV pump excitation, much above the lowest energy A exciton of four to six layers of MoS2 nanosheets (~1.84 eV), generates excitons and free carriers. The excitons decay quickly within ~3 ps due to the defect capture via the Shockley–Read–Hall mechanism. In contrast, free carriers show slower recombination (~1000 ps), which is an order of magnitude larger than the exciton recombination time. We verified this idea by exciting the sample with 1.94–2.22 eV pump excitations that predominantly generate excitons decaying within ~3 ps. Our systematic studies in few‐layer MoS2 nanosheets reveal crucial information on the unexplored domain of excitons and free carriers recombination in the presence of defects for several optoelectronic applications.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
