A Curved Graphene Nanoribbon with Multi-Edge Structure and High Intrinsic Charge Carrier Mobility

Abstract

Structurally well-defined graphene nanoribbons (GNRs) have emerged as highly promising materials for the next-generation nanoelectronics. The electronic properties of GNRs critically depend on their edge topologies. Here, we demonstrate the efficient synthesis of a curved GNR (cGNR) with a combined cove, zigzag, and armchair edge structure, through bottom-up synthesis. The curvature of the cGNR is elucidated by the corresponding model compounds tetrabenzo­[a,cd,j,lm]­perylene (1) and diphenanthrene-fused tetrabenzo­[a,cd,j,lm]­perylene (2), the structures of which are unambiguously confirmed by the X-ray single-crystal analysis. The resultant multi-edged cGNR exhibits a well-resolved absorption at the near-infrared (NIR) region with a maximum peak at 850 nm, corresponding to a narrow optical energy gap of ∼1.22 eV. Employing THz spectroscopy, we disclose a long scattering time of ∼60 fs, corresponding to a record intrinsic charge carrier mobility of ∼600 cm2 V–1 s–1 for photogenerated charge carriers in cGNR.

Band structure modulation by methoxy-functionalization of graphene nanoribbons

“…As a purely optical technique, OPTP measurements have been demonstrated as a powerful method to investigate the photoconductivity dynamics of charge carriers in nanomaterials, in a contact-free and noninvasive manner. 20,22,[53][54][55] Figures 4a,b compare the photoconductivity dynamics for GNR-H 10 and GNR-OMe 9, which were dispersed in 1,2,4-trichlorobenzene for the measurements. In both cases, we observe a transient rise of real photoconductivity due to the injection of free carriers into GNRs following beyond-bandgap optical excitations (by 2.25 eV laser pulses).…”

“…As a purely optical technique, OPTP measurements have been demonstrated as a powerful method to investigate the photoconductivity dynamics of charge carriers in nanomaterials, in a contact-free and noninvasive manner. 20,22,[56][57][58] Fig. 4a and b compare the photoconductivity dynamics for GNR-H 10 and GNR-OMe 9, which were dispersed in 1,2,4-trichlorobenzene for measurements.…”

“…9,10,12 While armchair and zigzag GNRs possess planar structures, cove and fjord edges induce non-planarity, which is advantageous to improve the solubility of the GNRs by suppressing the p-p interactions. [20][21][22] In addition, non-planarity is also predicted to affect the electronic properties of GNRs, [23][24][25][26] but its precise effects still remain unexplored. 20,21,[27][28][29] For the investigation of non-planar GNRs, the solution synthesis protocols can be more advantageous than the onsurface methods.…”

Synthesis of Nonplanar Graphene Nanoribbon with Fjord Edges

“…On the other hand, Liu, Mai, and colleagues demonstrated a solution synthesis of the first example of long curved GNRs featuring a combination of cove, zigzag, and armchair edges. 23 Very recently, Rubin and co-workers reported the synthesis of a nitrogen-doped fjord-edged GNR via solid-state topochemical polymerization, although its nonplanarity was not discussed and the resulting GNRs seemed to have only limited solubility. 24 Thus, the development of highly twisted fjord-edged GNRs in solution has remained elusive.…”

Design, Synthesis and Properties of Azulene-Based BN-[4]Helicenes※

“…图式 1 薁基螺烯 1a/1b 和 2 的合成路线 Scheme 1 Synthesis routes of azulene-embedded helicenes 1a/1b and 2 如图 1 所示, 1a, 1b 和 2 中 H-1 的化学位移分别位 于 δ 8.70, 8.75 和 8.75, H-2 的化学位移分别位于 δ 9.41, 9.45 和 9.45, 其相对于 S4 中的 H-1 (δ 7.55)和 H-2 (δ 7.74)明显向低场移动, 原因是螺旋结构形成了湾区 化 学 学 报 研究论文 (cove-region) [19] , 该变化趋势和[4]螺烯一致 [20] . 另一方 面, 1b 中的 H-3 (δ 8.38)与 1a (δ 8.92)和 2 (δ 8.87)中的 H-3 相比受到的屏蔽效应增大, 化学位移移向高场.…”