The emission enhancement of quantum emitters is crucial for the development of quantum technologies based on single-photon sources. Metallic nanoparticles have been initially considered with this aim due to their ability to produce strong electromagnetic energy concentrations (hot spots) at the emitters' position. However, metallic nanostructures suffer from high non-radiative losses. To address this, high-refractive-index dielectric (HRID) nanoparticles, characterized by exhibiting Mie resonances with negligible absorption in specific spectral ranges, have emerged as an alternative. Additionally, dielectric nanoparticles can exhibit magnetic responses despite being non-magnetic materials. The interference between electric and magnetic resonances can result in directional properties, potentially increasing the collection efficiency of scattered radiation. Despite these advantages, HRID nanoparticles do not enhance light emission as much as metallic ones. In contrast, hybrid metal–dielectric nanostructures can offer greater functionality and efficiency compared to purely metallic or dielectric nanoparticles.

Recently, moderate-refractive-index (MRI) dielectric nanoparticles have been numerically and experimentally demonstrated to enhance the emission of excitons in 2D materials. These MRI materials (n≈2.2) exhibit broadband Mie resonances, enabling the simultaneous enhancement of multiple excitons.

In this work, different dimer configurations are analyzed with the objective of enhancing the photoluminescence signal of a quantum dot located in the dimer gap. Dimers of pure metallic, pure HRID, pure MRI dielectric, and hybrid combinations of metallic and dielectric nanoparticles, either HRID or MRI, are numerically explored. For each case, the excitation enhancement, Purcell factor at the emission wavelengths, and directionality are studied by means of the Finite Element Method in COMSOL Multiphysics. Through the results obtained, we can conclude that the combination of MRI and HRID nanoparticles can provide large values of the photoluminescence signal (4–4.8 for MRI combinations and 5.4-7 for HRID) with low losses (with the ratio of the radiative to non-radiative power being between 0.63 and 0.7).