Localized Exciton Anatomy and BandGap Energy Modulation in 1D MoS₂ Nanostructures

Abstract

This study presents an in-depth investigation of the electronic properties and bandgap energy distribution in 1D molybdenum disulfide (1D-MoS2) nanostructures. Through a combination of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and electron energy-loss spectroscopy (EELS), it reveals significant differences between 1D-MoS2 nanostructures and their 2D counterparts, shedding light on their localized exciton behavior and their bandgap energy modulation within the nanostructures. Excitonic peaks at around 2 and 3 eV appear localized at the ends or along the sides of the 1D-MoS2 nanostructures, while the plasmonic resonance at 8.3 eV retains its inner-region localization. It demonstrates the spatial dependence of the bandgap energy, with the central region exhibiting a bandgap of approximately 1.2 eV, consistent with bulk MoS2, while regions characterized by curvature-induced local strain fields exhibit instead a noticeable reduction. The findings provide valuable insights into the intricate relationship between excitonic behavior and bandgap sensitivity in 1D-MoS2 nanostructures, streamlining the design and optimization of nanophotonic and optoelectronic devices.