Doping of Graphene Nanoribbons via Functional Group Edge Modification.

Carbonell-Sanromà, Eduard; Hieulle, Jeremy; Vilas-Varela, Manuel; Brandimarte, Pedro; Iraola, Mikel; Barragán, Ana; Li, Jingcheng; Abadia, Mikel et al. · ACS Nano · 2017

basic_science · Level V

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Abstract

We report the on-surface synthesis of 7-armchair graphene nanoribbons (7-AGNRs) substituted with nitrile (CN) functional groups. The CN groups are attached to the GNR backbone by modifying the 7-AGNR precursor. Whereas many of these groups survive the on-surface synthesis, the reaction process causes the cleavage of some CN from the ribbon backbone and the on-surface cycloisomerization of few nitriles onto pyridine rings. Scanning tunneling spectroscopy and density functional theory reveal that CN groups behave as very efficient n-dopants, significantly downshifting the bands of the ribbon and introducing deep impurity levels associated with the nitrogen electron lone pairs.