Controlling Electron Mobility of Strongly Coupled Organic Semiconductors in Mirrorless Cavities

Abstract

AbstractRecent experiments on the strong light‐matter coupling between an organic semiconductor and a plasmonic mode propose an unconventional way to enhance conductivity. Herein, it is shown that mirrorless cavities can boost conductivity by simply structuring the refractive indices of the multilayers in a commercially available metal oxide semiconductor field effect transistor (MOSFET). Perylene diimide (an organic semiconductor dye) molecules are deposited on a MOSFET device. The refractive index mismatch between the silicon/silicon dioxide/dye/air results in light confinement. The frequency of this confined light is tuned by changing the thickness of the organic semiconductor layer. Interestingly, an increase in electron mobility was observed once the electronic transition of the dye molecules and the second‐order cavity mode enter into the strong coupling regime. Whereas resonance tuning to the first‐order mode does not affect the electron transport. Here, the system is still in a weak coupling regime. These results are further correlated by experimental dispersion measurements and supported with transfer matrix simulations. The increase in electron mobility is not large due to high dissipation or low‐quality factors of the cavity modes. However, the mirrorless configuration presented here may offer a simpler way of boosting the properties of functional materials.