Charge transport in cove-type graphene nanoribbons: The role of quasiparticles

Tiago de Sousa Araújo Cassiano, Leonardo Evaristo de Sousa*, Luiz Antônio Ribeiro Junior, Geraldo Magela e Silva, Pedro Henrique de Oliveira Neto

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Previous reports indicate that cove-type graphene nanoribbons (CGNR) may present high intrinsic charge mobility of almost 15,000 cm2/Vs. Still, with experimental estimates varying from 150 to 15,000 cm2/Vs. Typically, theoretical mobilities are obtained from methods such as the Drude-Smith model, which tends to neglect the electron-phonon coupling mechanism, or the Boltzmann transport equation, that considers only acoustic phonons. As such, more thorough approaches are needed. In this work, we simulated charge transport in 4-CGNR by explicitly contemplating the lattice collective behavior. The nanoribbon is simulated by a two-dimensional Su-Schrieffer-Heeger (SSH) tight-binding model with electron-phonon coupling and considering all phonon modes. Results show the rise of two quasiparticles: polaron and bipolaron. We probed their dynamical properties by including the presence of an external electric field. Findings indicate that each carrier has a characteristic transport regime that is deeply related to phonon collision interactions. Model derived mobilities for polarons and bipolarons reach up to 18,000 cm2/Vs and 1500 cm2/Vs, respectively. Furthermore, calculations reveal the carriers to be highly efficient charge transporters, with a field independent low effective mass and notable mobility, delivering a better performance than other narrow GNRs. All presented features place the CGNR as a potential base material of future high-quality organic-based optoelectronic devices. The work also contributes to the theoretical understanding of transport physics in highly confined materials.
Original languageEnglish
Article number117056
JournalSynthetic Metals
Volume287
Number of pages9
ISSN0379-6779
DOIs
Publication statusPublished - 2022

Keywords

  • SSH
  • Graphene
  • Polarons
  • Bipolarons
  • Charge transport
  • GNR

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