Interlayer excitons in transition-metal dichalcogenide heterobilayers combine high binding energy and valley-contrasting physics with long optical lifetime and strong dipolar character. Their permanent electric dipole enables electric-field control of emission energy, lifetime, and location. Device material and geometry impacts the nature of the interlayer excitons via their real- and momentum-space configurations. Here, we show that interlayer excitons in MoS2/MoSe2 heterobilayers are formed by charge carriers residing at the Brillouin zone edges, with negligible interlayer hybridization. We find that the moir\'e superlattice leads to the reversal of the valley-dependent optical selection rules, yielding a positively valued g-factor and cross-polarized photoluminescence. Time-resolved photoluminescence measurements reveal that the interlayer exciton population retains the optically induced valley polarization throughout its microsecond-long lifetime. The combination of long optical lifetime and valley polarization retention makes MoS2/MoSe2 heterobilayers a promising platform for studying fundamental bosonic interactions and developing excitonic circuits for optical information processing.
@article{arxiv.2406.02708,
title = {Nature of long-lived moir\'e interlayer excitons in electrically tunable MoS$_{2}$/MoSe$_{2}$ heterobilayers},
author = {Evgeny M. Alexeev and Carola M. Purser and Carmem M. Gilardoni and James Kerfoot and Hao Chen and Alisson R. Cadore and Bárbara L. T. Rosa and Matthew S. G. Feuer and Evans Javary and Patrick Hays and Kenji Watanabe and Takashi Taniguchi and Seth Ariel Tongay and Dhiren M. Kara and Mete Atatüre and Andrea C. Ferrari},
journal= {arXiv preprint arXiv:2406.02708},
year = {2024}
}