Tuning the deposition of molecular graphene nanoribbons by surface functionalization

Abstract

We show that individual, isolated graphene nanoribbons, created with a molecular synthetic approach, can be assembled on functionalised wafer surfaces treated with silanes. The use of surface groups with different hydrophobicities allows tuning the density of the ribbons and assessing the products of the polymerisation process.

Diels–Alder polymerization: a versatile synthetic method toward functional polyphenylenes, ladder polymers and graphene nanoribbons

“…97 For the fabrication of single-GNR-based devices, it is essential to deposit isolated GNRs, which was achieved by immersing alkyl-functionalized Si/SiO 2 substrates in a dispersion of GNR 65a, revealing a length over 500 nm visualized by AFM ( Figure 4a). 98,99 The length distribution of GNR 65a observed by AFM was in good agreement with the molecular weight distribution of the corresponding alkylated PP precursor 64a based on their GPC analysis. 98 Such individual GNR strands could then be used to fabricate single molecule devices, exhibiting electrical conduction ( Figure 4b).…”

“…98,99 The length distribution of GNR 65a observed by AFM was in good agreement with the molecular weight distribution of the corresponding alkylated PP precursor 64a based on their GPC analysis. 98 Such individual GNR strands could then be used to fabricate single molecule devices, exhibiting electrical conduction ( Figure 4b). 99 Moreover, thin film devices based on GNR 65a were also fabricated by drop casting the GNR dispersion on the functionalized Si/SiO 2 substrates.…”

New advances in nanographene chemistry

“…16) also proved to be applicable for GNR 129c to afford chlorinated GNR 130, which demonstrated lowered optical bandgap as expected by the theory (Fig. 249,250 By treating the Si/SiO 2 substrate with silane derivatives with different hydrophobicities, it is possible to control the density of the deposited GNRs. 198,247 Furthermore, deposition of isolated strands of GNR 129a was achieved by immersing a functionalized Si/SiO 2 substrate in a diluted dispersion of 129a, demonstrating that the GNRs extended over 600 nm.…”

“…24). 250 Transistor devices could be fabricated by directly depositing metal electrodes on such GNR strands, which exhibited good electrical conduction through the isolated GNRs. 249,250 By treating the Si/SiO 2 substrate with silane derivatives with different hydrophobicities, it is possible to control the density of the deposited GNRs.…”

Polycyclic aromatic hydrocarbons in the graphene era

“…Similarly, different GNRs have been obtained by A 2 B 2 -type Diels-Alder polymerization or AAtype Yamamoto polymerization, but the obtained GNRs were still shorter than 100 nm, posing a major challenge to the fabrication of single-ribbon devices [96,[127][128][129]. To address this problem, Narita, Feng and Müllen et al [130,131] developed an AB-type Diels-Alder polymerization to achieve liquid-phase-processable GNRs longer than 600 nm ( Figure 16(b)). This achievement has not only allowed for the investigation of the fundamental physics of such structurally well-defined GNRs [132][133][134] but also promoted the fabrication of GNR-based devices by solution processing [135,136].…”