Tuning Light‐Matter Interaction in 2D Bi₂Se₃ Through Plasmonic Particle Coupling

Bismuth selenide (Bi 2 Se 3 ), a topological insulator, exhibits helicity‐preserving photoluminescence (PL) at optical wavelengths due to strong spin‐orbit coupling, which locks massless electrons and massive holes on the surface in chiral spin‐momentum textures. This unique light‐emitting property makes Bi 2 Se 3 a promising candidate for optoelectronic applications. However, its low PL efficiency and limited emission control hinder its full potential. In this study, 2D Bi 2 Se 3 crystals are synthesized via a simple chemical method, and a hybrid system integrating gold nanoparticles (Au NPs) are developed. This integration induces hybridization among Au‐5 d , Se‐4 p , and Bi‐6 p orbitals, introducing a new recombination pathway, as evidenced by both PL studies and first‐principles calculations. An enhancement in the PL intensity is observed in Au‐Bi 2 Se 3 hybrid samples compared to bare Bi 2 Se 3 , attributed to electron transfer from Au to Bi 2 Se 3 , as confirmed by Raman spectroscopy and density functional theory calculations. Systematic tuning of NP decoration enables the modulation of exciton‐plasmon coupling, leading to notable changes in the PL line shape of Bi 2 Se 3 . Additionally, an increased degree of circular polarization is observed in the hybrid system. These findings highlight the potential of Bi 2 Se 3 for next‐generation optoelectronic devices and tunable light‐emitting applications.