Energy Exchange and Coherent Behavior of Monolayer TMD Polaritonic Systems in All-Dielectric Metasurfaces Supporting Quasi-Bound States in the Continuum.

Room-temperature strong light-matter coupling in two-dimensional transition metal dichalcogenides (TMDs) is crucial for the development of polaritonic devices. In this work, we construct an all-dielectric metasurface platform supporting quasi-bound states in the continuum (q-BICs) and achieve strong coupling with four representative monolayer TMDs (MoSe2, MoS2, WS2, and WSe2) through tailored geometric scaling for zero-detuning matching. Based on the coupled oscillator model (COM) and the Heisenberg-Langevin model, we systematically analyze the coupling characteristics and polaritonic dynamics of these customized hybrid systems. The results show that the tailored MoSe2-cavity system achieves the maximum coupling strength (36.8 meV) and the fastest energy exchange, whereas the customized WSe2-cavity system demonstrates optimal coherence stability enabled by the highest cooperativity (C = 3.50). This study elucidates how the synergistic interplay between the materials' excitonic properties and the customized photonic environments decouples the energy exchange rate from coherence stability. These findings establish a practical configuration design framework for room-temperature polaritonic devices, paving the way for targeted applications that require either ultrafast responses or sustained polaritonic coherence.