where λ is the reorganization energy, Ω is the characteristic frequency of the phonon modes, and η is the coupling strength between exciton and phonon. The parameters used in the model are as given in Table . I. These are typical parameters for the recently explored CdSe Nanoplatelet coupled to a cavity. To explore the effect of a few molecules (N = 5) and more realistic collective coupling condition (N = 10 6 ). The half Rabi splitting √ N ℏg c is kept invariant as the number of sites N changes, which is equivalent to scaling g c with √ N . Fig. presets the schematic for the model system considered in this work, with an energy diagram of the relevant states as well as the J(ω)/(1 -e -βℏω ) function. Here, we consider three cases for the light-matter detuning, a zero detuning ∆ = 0 case where cavity mode is set to be resonant with the bare site excitation, a positive detuning ∆ = 142 meV chosen such that the transition energy between dark states D and UP is in close resonance with the maximum of J(ω)/(1 -e -βℏω ), such that the transition rates involving UP is maximized, and a negative detuning ∆ = -142 meV where transition rates involving LP is maximized.