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In this Perspective, we present that polariton modes hosted in two-dimensional (2D) materials can be used to increase and control light–matter interactions at the nanoscale. We analyze the optical response of the most used 2D material nanostructures that support plasmon, exciton, and phonon polariton modes. Polariton characteristic lengths are used to assess the hybrid light–matter modes of different 2D material monolayers and nanoribbons. We present that the 2D material nanodisk can act like a cavity that supports localized polariton modes, which can be excited by a nearby placed quantum system to present ultra-fast and ultra-bright operation. The key to achieve high quality 2D polariton modes is to reduce material losses. Thus, state-of-the-art exfoliation, chemical vapor deposition, and transferring techniques of 2D materials are introduced to fabricate nanostructures that fulfill the stringent requirements of applications in photonics, optoelectronics, and quantum technologies. [ABSTRACT FROM AUTHOR]

Plasmon–exciton interactions between noble metal nanostructures and two-dimensional transition metal dichalcogenides have drawn great interest due to their significantly enhanced optical properties. Plasmon resonance of noble metal nanoparticles and plasmon–exciton interactions are strongly dependent on the particle morphology. Single-particle spectroscopic studies can overcome the ensemble average effects of sample inhomogeneity to unambiguously reveal the effects of the particle morphology. In this work, plasmon modulated emission of MoS2 in various plasmon–MoS2 hybrid structures has been studied on the single-particle level. Gold (Au) nanoantennas of different shapes including nanosphere, nanorod, nanocube, and nanotriangle with similar overall dimensions, which have different sharp tips and contact areas with MoS2, have been chosen to explore the particle shape effects. Different extent of enhancement in photoluminescence (PL) of MoS2 was observed for Au nanoantennas of different shapes. It was found that Au nanotriangles gave the highest enhancement factor, while Au nanospheres gave the lowest enhancement factor. The numerical simulation results show that the dominant contribution arises from an increased quantum yield, while enhanced excitation efficiency just plays a minor role. The quantum yield enhancement is affected by both the sharp tips and contact mode of the Au nanoantenna with MoS2. Polarization of the MoS2 emission was also found to be modulated by the plasmon mode of the Au nanoantenna. These single-particle spectroscopic studies allow us to unambiguously reveal the effects of the particle morphology on plasmon enhanced PL in these nanohybrids to provide a better understanding of the plasmon–exciton interactions. [ABSTRACT FROM AUTHOR]