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<p>Dark excitons in two-dimensional (2D) transition metal dichalcogenide semiconductors (TMDs) have long radiative lifetimes, making them promising for quantum information and optoelectronics. Their detection and control are challenging due to weak out-of-plane dipole moments and momentum mismatch with free-space photons. Using ab initio calculations (DFT + G<sub>0</sub>W<sub>0</sub> + BSE), a Wannier–Mott exciton model, and a numerical solution of the Laplace equation, we model the tip-enhanced near-field and its interaction with excitons via first-order time-dependent perturbation theory. Focusing on WSe<sub>2</sub> monolayers, we show that the strong out-of-plane near field from a metallic tip enhances radiative recombination of spin-forbidden dark excitons by providing additional in-plane momentum to overcome momentum mismatch. We also analyze substrate screening effects on excitonic properties and lifetimes. Our results offer a theoretical framework for controlled activation of dark excitons toward quantum and nanophotonic applications.</p>

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Enhancement, brightening and control of radiative emission of dark exciton in WSe2 monolayer by plasmonic effect

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年10月23日

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  • Adlen Smiri,
  • F. R. Pratama,
  • Takeshi Nakanishi

摘要

Dark excitons in two-dimensional (2D) transition metal dichalcogenide semiconductors (TMDs) have long radiative lifetimes, making them promising for quantum information and optoelectronics. Their detection and control are challenging due to weak out-of-plane dipole moments and momentum mismatch with free-space photons. Using ab initio calculations (DFT + G0W0 + BSE), a Wannier–Mott exciton model, and a numerical solution of the Laplace equation, we model the tip-enhanced near-field and its interaction with excitons via first-order time-dependent perturbation theory. Focusing on WSe2 monolayers, we show that the strong out-of-plane near field from a metallic tip enhances radiative recombination of spin-forbidden dark excitons by providing additional in-plane momentum to overcome momentum mismatch. We also analyze substrate screening effects on excitonic properties and lifetimes. Our results offer a theoretical framework for controlled activation of dark excitons toward quantum and nanophotonic applications.