Emerging Device Applications From Strong Light-Matter Interactions in 2D Materials.

Two-dimensional (2D) semiconductors provide a powerful platform for highly compact optoelectronic devices, spanning solar cells, photodetectors, light-emitting diodes (LEDs), and lasers. In these materials, tightly bound excitons dominate key metrics such as absorption strength, quantum efficiency, response speed, and spectral purity. When driven into the strong light-matter coupling regime, excitons hybridize with cavity photons, plasmons, or magnons to form exciton-, plasmon-, and magnon-polaritons, enabling engineered dispersion, low-threshold lasing, ultrafast modulation, and enhanced nonlinear functionality within footprint-limited architectures. Earlier reviews have focused on the fundamentals of strong coupling, band engineering, and realizing strong coupling with a variety of 2D materials. In this review, we will discuss different device architectures based on exciton and polaritons-based systems, integrating 2D materials and heterostructures with dielectric cavities, metasurfaces, waveguides, and hybrid metal/2D magnet platforms. We emphasize design strategies based on the best figures of merit for solar cells, photodetectors, and lasers from exciton- and polariton-based systems. Finally, we will discuss the routes to on-chip integration of LEDs from all-2D materials-based devices for next-generation photonic integrated circuits. Further, we will discuss advanced electron microscopy and nano-imaging to map polaritonic fields and exciton distributions, linking nanoscale coupling to macroscopic device behavior and outlining a roadmap for next-generation exciton/polariton devices.