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

• Autor(a) principal: Cassiano, Tiago de Sousa Araújo
• Data de Publicação: 2022
• Outros Autores: Sousa, Leonardo Evaristo de, Ribeiro Júnior, Luiz Antônio, Silva, Geraldo Magela e, Oliveira Neto, Pedro Henrique de
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UnB
• Texto Completo: http://repositorio2.unb.br/jspui/handle/10482/46884; https://doi.org/10.1016/j.synthmet.2022.117056
• topic: Grafeno; SSH; Polaron; Bipolaron; Transporte de carga; Nanofitas de grafeno

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.