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HL: Fachverband Halbleiterphysik

HL 3: 2D Materials I – Excitonic properties

HL 3.12: Vortrag

Montag, 9. März 2026, 12:30–12:45, POT/0081

Dark exciton activation in WSe₂ monolayer by tip-enhanced photoluminescence spectroscopy — Adlen Smiri, Fenda Rizky Pratama, and •Takeshi Nakanishi — MathAM-OIL AIST, Sendai, Japan

Dark excitons in 2D transition metal dichalcogenide semiconductors are characterized by long lifetimes, making them highly attractive candidates for quantum computing and optoelectronics.The purpose of this paper is to theoretically address the interactions between local electromagnetic fields and dark excitonic states, and 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 [1]. Using ab initio calculations, 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 demonstrate that the activation of dark excitons is attributed to the strong z-component of the near field induced by the tip. 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.

[1] Adlen Smiri, F. R. Pratama and Takeshi Nakanish, npj 2D Materials and Applications 9, 88 (2025)

Keywords: exciton; transition metal dichalcogenide; tip-enhanced photoluminescence; ab initio calculations; theory