Laterally extended atomically precise graphene nanoribbons with improved electrical conductivity for efficient gas sensing

Abstract

Narrow atomically precise graphene nanoribbons hold great promise for electronic and optoelectronic applications, but the previously demonstrated nanoribbon-based devices typically suffer from low currents and mobilities. In this study, we explored the idea of lateral extension of graphene nanoribbons for improving their electrical conductivity. We started with a conventional chevron graphene nanoribbon, and designed its laterally extended variant. We synthesized these new graphene nanoribbons in solution and found that the lateral extension results in decrease of their electronic bandgap and improvement in the electrical conductivity of nanoribbon-based thin films. These films were employed in gas sensors and an electronic nose system, which showed improved responsivities to low molecular weight alcohols compared to similar sensors based on benchmark graphitic materials, such as graphene and reduced graphene oxide, and a reliable analyte recognition. This study shows the methodology for designing new atomically precise graphene nanoribbons with improved properties, their bottom-up synthesis, characterization, processing and implementation in electronic devices.

Graphene Nanoribbons: On‐Surface Synthesis and Integration into Electronic Devices

“…[ 89,91 ] The lateral extension of the chevron‐type GNR resulted in a small reduction in the bandgap from 1.61 to 1.38 eV according to density functional theory (DFT) calculations. [ 92 ]…”

“…[ 91 ] The widening of the chevron GNR resulted in a reduction in the bandgap from 1.61 to 1.38 eV according to DFT calculations. [ 92 ] The heterojunction obtained by combining the chevron‐type GNR and the laterally extended GNR demonstrated the possibility of engineering complex GNR‐based nanostructures.…”

Effect of Edge Functionalization on the Bottom‐Up Synthesis of Nano‐Graphenes

“…Various bottom‐up GNRs have been reported to date, including GNRs with armchair edges, zigzag edges, chiral edges, hetero atom doping and edge functionalization . The preliminary demonstration of electronic devices was also reported, in which GNRs without intentional doping were used in the channel. While the effect of halogen, substrate, and impurities as well as growth kinetics in on‐surface Ullman coupling have been reported so far, the mechanism of on‐surface polymerization is not yet thoroughly investigated.…”

Nanographenes as electron-deficient cores of donor-acceptor systems

“…As molecularly defined cutouts of the graphene lattice, nanographenes (NGs) have been developed to deduce intrinsic structure-property correlations 1 – 3 . Among various functional characteristics of NGs, their extended sp 2 -conjugated carbon skeleton offers intriguing optical absorption, photoluminescence and charge transport properties 4 – 7 and thus promising potential in electronics 8 , 9 and optoelectronics 10 . The electron-rich nature of NGs qualifies them as typical p-type semiconductors in organic field-effect transistors 11 – 14 and as electronic donors in organic photovoltaics 14 – 16 .…”