2D‐Material‐Fused High‐Emittance Plasmo–Photonic Metasurfaces

Transition metal dichalcogenides (TMDC) are a family of atomic-layer two-dimensional materials (2dMs). Many researches have attempted to reinforce the unique properties by incorporating artificially designed nanostructures. Here, a highly photoluminescence (PL) enhancing platform is reported that was formed by combining high-emittance plasmo--photonic metasurfaces with a large-area 2dM, which was a continuous monolayer of TMDC of cm² dimension. It is experimentally demonstrated that the 2dM-PL intensity at room temperature was enhanced by more than 1030-fold in comparison with that observed on the flat gold film regions. The enhancement is associated with spectral transformation indicating a resonant effect of the metasurfaces. It is moreover revealed that the confocal PL image originates from a coherent single-mode emission that forms a photon number distribution obeying the Poisson probability distribution. Thus, the 2dM-fused metasurfaces function as efficient coherent quantum light sources. PL decay-time analysis also reveals the coexistence of two components in the enhanced PL. The fast component exhibits a lifetime of 18 ps whereas the slow component decays at 4.4 ns. Both components are most likely to undergo radiative processes, which indicates that metal-induced PL quenching is suppressed on these 2dM-fused metasurfaces. The long lifetime component is ascribed to an excitonic intervalley transition.