Ultrafast Bright-to-Dark Exciton Relaxation in Bilayer Borophene Driven by Strong Excitonic Effects.

Authors

Yunlei Wang, Haifeng Lv, Xiaojun Wu

Published in

Nano letters. May 20, 2025. Epub May 20, 2025.

Abstract

Exciton dynamics in the recently discovered bilayer borophene (BL-α₅, consisting of two stacked v_1/12 boron sheets) are of great interest due to this material's promising electronic and optical properties for nano-optoelectronic applications. Using a GW plus real-time Bethe-Salpeter equation (GW-rtBSE) approach and ab initio nonadiabatic molecular dynamics (NAMD), we identify a Frenkel-type lowest-energy bright exciton and a spatially delocalized dark exciton in BL-α₅, with large binding energies of ∼700 and ∼502 meV, respectively. The electron-hole (e-h) Coulomb interaction (exciton effect) dominates over electron-phonon (e-ph) scattering, playing a pivotal role in an ultrafast bright-to-dark exciton transition with a relaxation time of ∼150 fs. Furthermore, the dark excitons undergo nonradiative recombination on a picosecond time scale (∼14 ps at room temperature). These results provide a theoretical foundation for potential nano-optoelectronic and light-energy harvesting applications of bilayer borophene.

PMID:
40391418
Bibliographic data and abstract were imported from PubMed on 20 May 2025.

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