Organic-inorganic polaritonics: Linking Frenkel and Wannier-Mott excitons

In recent years, organic materials have emerged as promising candidates for a variety of light-harvesting applications ranging from the infrared to the visible regions of the electromagnetic spectrum. Their enhanced excitonic binding energies and large transition dipole moments enable strong coupling with light, with some systems already reaching the ultrastrong-coupling regime. In contrast, a wide range of two-dimensional (2D) materials has been extensively explored in the literature, exhibiting high exciton stability and strong electron-hole coupling due to reduced screening effects. In this Letter, we present a microscopic model describing the interaction of 2D materials and organic molecular aggregates in an optical cavity. We predict the formation of a hybrid Wannier-Mott-Frenkel exciton polariton with an enhanced Rabi splitting, exceeding that of the pure organic cavity by several tens of meV. To elucidate this phenomenon, we examine a cavity with 2D tungsten sulfide and a cyanine dye, where this enhancement corresponds to a $5%$ increase relative to the organic cavity. The complementary characteristics of Wannier-Mott and Frenkel excitons enable the formation of tunable polariton states that merge into a single hybrid state as a function of detuning, allowing for dual Rabi splitting mechanisms. This provides a promising platform for exploring quantum optical phenomena in both the strong- and ultrastrong-coupling regimes.