Bosonic Charge Carriers in Necklace-like Graphene Nanoribbons.

Abstract

Motivated by the success of graphene in flat optoelectronics, several carbon allotropes have recently been proposed. One of these allotropes, graphene nanoribbons (GNRs) with a singular "necklace-like" atomic structure, was recently synthesized through a bottom-up chemical approach. The absorption spectrum exhibited a band gap of 1.4 eV for this novel GNR geometry. Guided by its exciting electronic and structural properties, investigations should be performed to outline the major features of this material focused on expanding organic-based energy conversion and storage applications. In particular, the formation and dynamics of charge carriers are crucial in defining the material's performance. Here we describe the formation and transport of charge carriers in necklace-like graphene nanoribbons (NGNRs). A 2D tight-binding Hamiltonian endowed with lattice relaxation effects constitutes the basis of the theoretical approach employed to examine the carrier formation and dynamics in these lattices. Results demonstrate that polarons and effective boson species are spontaneously generated in NGNRs by the addition of holes or electrons to the system. Both types of generated quasiparticles are dynamically stable and can move at surprisingly low electric-field regimes. Remarkably, the formation of effective bosons is a process triggered by a higher density of added charges. The understanding of the carriers' formation and transport in NGNRs can pave the way for their broad usage in producing novel optoelectronic applications, added to the possibility of Bose-Einstein condensate phenomena.