Dielectric Nanoparticle Dimers on a Mirror for Enhanced Photoluminescence of Quantum Dots.

Nanoantennas for enhancing quantum emitters' response have attracted considerable attention, particularly those based on hybrid metal-dielectric configurations. However, it remains a challenge to simultaneously enhance excitation and emission while maintaining directionality. In this work, novel hybrid metal-dielectric designs based on the nanoparticle-on-mirror architecture are analyzed to maximize the photoluminescence of quantum dots. The proposed nanostructure consists of a silicon nanocylinder dimer placed on an aluminum substrate separated by a thin spacer layer embedding randomly distributed CdSe/ZnS quantum dots. By combining a semianalytical approach based on image theory with numerical simulations, it is demonstrated that the interaction between the nanoparticles in the dimer, which gives rise to new modes, can lead to enhanced photoluminescence. The analysis is further extended to periodic metasurfaces composed of arrays of these dimer unit cells, showing that the enhanced excitation and directional emission are preserved in large-area devices. These results are relevant for the development of single-photon sources, single-molecule detection, and high-brightness nanophotonic light sources for displays and bioimaging technologies.