Overall, due to entropic contribution to the free energy, the lower polariton is more reactive to population transfer processes to higher-energy states (i.e. dark states) than it is generally anticipated when only considering their energetic ordering. Coupling to the cavity can also enhance excitation energy transfer and lead to faster energy transport, especially in materials. Using a generalized Tavis-Cummings Hamiltonian, Ref. 134 simulates the transport properties of organic crystals when coupled to plasmonic nanoparticle arrays as illustrated in Fig. . They find that the propagation length when coupling to a cavity is significantly larger than outside the cavity. Their simulations suggest that non-adiabatic transitions in combination with cavity decay dominate the transport mechanism and set an upper limit to the distance over which energy can be transported.