Experimental Observation of Strong Exciton Effects in Graphene Nanoribbons

Abstract

Graphene nanoribbons (GNRs) with atomically precise width and edge structures are a promising class of nanomaterials for optoelectronics, thanks to their semiconducting nature and high mobility of charge carriers. Understanding the fundamental static optical properties and ultrafast dynamics of charge carrier generation in GNRs is essential for optoelectronic applications. Combining THz spectroscopy and theoretical calculations, we report a strong exciton effect with binding energy up to 700 meV in liquid-phase-dispersed GNRs with a width of 1.7 nm and an optical bandgap of 1.6 eV, illustrating the intrinsically strong Coulomb interactions between photogenerated electrons and holes. By tracking the exciton dynamics, we reveal an ultrafast formation of excitons in GNRs with a long lifetime over 100 ps. Our results not only reveal fundamental aspects of excitons in GNRs (gigantic binding energy and ultrafast exciton formation etc.), but also highlight promising properties of GNRs for optoelectronic devices.

arXiv comment26 pages, 4 figures, 5 pages Supplementary Information

References in corpus (15)

• Ultrahigh electron mobility in suspended graphene
• Energy Band Gap Engineering of Graphene Nanoribbons
• Energy Gaps in Graphene Nanoribbons
• Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
• Electronic spin transport and spin precession in single graphene layers at room temperature
• Excitons in atomically thin transition metal dichalcogenides
• Exciton binding energies in carbon nanotubes from two-photon photoluminescence
• Optical properties of graphene nanoribbons: the role of many-body effects
• Mobility in Semiconducting Graphene Nanoribbons: Phonon, Impurity, and Edge Roughness Scattering
• Excitons versus electron-hole plasma in monolayer transition metal dichalcogenide semiconductors
• The ultrafast dynamics and conductivity of photoexcited graphene at different Fermi energies
• Vibrational properties of graphene nanoribbons by first-principles calculations
• Transient terahertz spectroscopy of excitons and unbound carriers in quasi two-dimensional electron-hole gases
• Excitonic Effects in the Optical Spectra of Graphene Nanoribbons
• Exciton absorption spectra in narrow armchair graphene nanoribbons in electric fields

Cited by in corpus (6)

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• Probing Carrier Dynamics in sp${}^3$-Functionalized Single-Walled Carbon Nanotubes with Time-Resolved Terahertz Spectroscopy
• Isolated Flat Bands and Physics of Mixed Dimensions in a 2D Covalent Organic Framework
• Understanding the optical properties of doped and undoped 9-armchair graphene nanoribbons in dispersion
• Excitons in planar quantum wells based on transition metal dichalcogenides