2017/09/12 by Zefang Wang, Yi-Hsin Chiu, Kevin Honz +2 · 163 citations
Chemistry · Engineering · Materials Science · Physics and Astronomy · #2D Materials and Applications #Atomic physics #Chemistry #Condensed matter physics #Degenerate energy levels #Dipole #Electric field #Exciton #Graphene research and applications #Heterojunction #Materials science #Molecular physics #Optoelectronics #Perovskite Materials and Applications #Physics #Semiconductor #cond-mat.mes-hall #cond-mat.mtrl-sci #van der Waals force
paper · pdf · doi:10.1021/acs.nanolett.7b03667
published in Nano Letters 18(1), 137-143 (American Chemical Society)
arxiv created 2017/09/12 · openalex publication_date 2017/12/14 · arxiv updated 2018/02/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
van der Waals heterostructures formed by stacking two-dimensional atomic crystals are a unique platform for exploring new phenomena and functionalities. Interlayer excitons, bound states of spatially separated electron–hole pairs in van der Waals heterostructures, have demonstrated potential for rich valley physics and optoelectronics applications and been proposed to facilitate high-temperature superfluidity. Here, we demonstrate highly tunable interlayer excitons by an out-of-plane electric field in homobilayers of transition metal dichalcogenides. Continuous tuning of the exciton dipole from negative to positive orientation has been achieved, which is not possible in heterobilayers due to the presence of large built-in interfacial electric fields. A large linear field-induced redshift up to ∼100 meV has been observed in the exciton resonance energy. The Stark effect is accompanied by an enhancement of the exciton recombination lifetime by more than two orders of magnitude to >20 ns. The long recombination lifetime has allowed the creation of an interlayer exciton gas with density as large as 1.2 × 10 11 cm –2 by moderate continuous-wave optical pumping. Our results have paved the way for the realization of degenerate exciton gases in atomically thin semiconductors.