Unique high-energy excitons in two-dimensional transition metal dichalcogenides

Two-dimensional (2D) transition metal dichalcogenides (TMDs), endowed with exceptional light–matter interaction strength, have become a pivotal platform in advanced optoelectronics, enabling atomically precise control of excitonic phenomena and offering transformative potential for engineering next-generation optoelectronic devices. In contrast to the narrowband absorption characteristics of conventional band-edge excitons, which are limited by the bandgap energy, high-energy excitons not only demonstrate broad momentum matching capability in the ultraviolet regime due to band nesting effects, but also exhibit distinct absorption peak signatures owing to robust excitonic stabilization under 2D confinement. These unique photophysical properties have established such systems as a prominent research frontier in contemporary exciton physics. This review primarily outlines the distinctive physical characteristics of high-energy excitons in TMDs from the perspectives of band structure, excitonic characteristics, and optical properties. Subsequently, we systematically delineate cutting-edge developments in TMD-based photonic devices exploiting high-energy excitonic band-nesting phenomena, with dedicated emphasis on the strategic engineering of nanoscale heterostructures for tailored optoelectronic functionality. Finally, the discussion concludes with an examination of the challenges associated with the design of high-energy exciton devices and their potential future applications.