Near infrared photoluminescence of the bottom-up produced 7-armchair graphene nanoribbons

Abstract

The narrow graphene nanoribbons (GNRs) are carbon based nanomaterials with interesting optical and electronic properties. We studied the photoluminescence properties of narrow graphene nanoribbons synthesized via the chemical vapor deposition method based on the bottom-up approach. The structure and quality of the synthesized GNR films were confirmed by measuring the Raman fingerprints of the 7-armchair graphene nanoribbons. The produced 7-armchair GNRs have a wide optical bandgap with an excitonic photoluminescence peak maximum at 608 nm (2.04 eV). At the same time, the 7-armchair GNR suspension has a bright photoluminescence in the infrared spectrum range with a peak maximum at 910 nm (1.36 eV). The relative intensity of this peak increases upon adding the p-type dopant to the GNR solution. The energy 1.36 eV of this luminescent transition is in good agreement with the theoretically predicted energy of the lowest bright trion state in the freestanding 7-armchair graphene nanoribbons. The demonstrated results can be beneficial for further study of narrow GNRs, especially in optics, and can be useful in applications of GNRs.