Atomically well-defined nitrogen doping for cross-plane transport through graphene heterojunctions

Zhang, Hewei; Zhou, Ping; Daaoub, Abdalghani; Sangtarash, Sara; Zhao, Shiqiang; Yang, Zixian; Zhou, Yu; Zou, Yu-Ling; Decurtins, Silvio; Häner, Robert; Yang, Yang; Sadeghi, Hatef; Liu, Shi‐Xia; Hong, Wenjing

doi:10.1039/d3sc00075c

Cited by 5 publications

(3 citation statements)

References 62 publications

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“…The reduction of the band gap by annulation of the phenyl rings is mainly based on stabilization of the LUMO energies, while HOMO levels are only slightly affected. [30,31] Stabilization of HOMO and LUMO energies of 3 a-c might be due to the improved contribution of the annulated phenyl rings to both frontier molecular orbitals (FMOs). Introduction of nitrogen in 3 b and 3 c leads to further reduction of both HOMO-und LUMO energy levels.…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, uncyclized compound 4 has an increased bandgap of 3.7 eV (Figure 5; Table 2). The reduction of the band gap by annulation of the phenyl rings is mainly based on stabilization of the LUMO energies, while HOMO levels are only slightly affected [30,31] . Stabilization of HOMO and LUMO energies of 3 a – c might be due to the improved contribution of the annulated phenyl rings to both frontier molecular orbitals (FMOs).…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and Properties of Diindeno[1,2,3‐cd:1′,2′,3′‐mn]pyrene and Two of Its Aza‐Analogs

Khomutetckaia,

Hildebrandt,

Ehlers

et al. 2023

Eur J Org Chem

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The incorporation of heteroatoms into polycyclic aromatic hydrocarbons (PAHs) has been recognized as valuable tool to alter their inherent optical and electrochemical properties and are thought as promising next‐generation semiconductor materials. We herein report the synthesis of diindenopyrene, a fragment of C70 and two of its nitrogen‐doped aza‐analogs. The developed synthetic procedure is based on Brønsted‐acid‐mediated cycloisomerization followed by Pd‐catalyzed C−H‐activation as key‐steps. The impact of N‐doping on the optical and electrochemical properties has been studied and the experimental results are supported by DFT calculations.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis and Properties of Diindeno[1,2,3‐cd:1′,2′,3′‐mn]pyrene and Two of Its Aza‐Analogs

Khomutetckaia,

Hildebrandt,

Ehlers

et al. 2023

Eur J Org Chem

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show abstract

“…Thus, a spin channel with a long spin lifetime and a long spin diffusion length is needed. Graphene is considered a very promising candidate for long-distance spin transport due to its weak spin-orbit coupling, long spin coherence length, high electrical mobility, and gate-tunable carrier concentration [19][20][21][22][23]. For example, Kamalakar et al demonstrated spin transport in a graphene channel over a channel length of 16 µm with a spin lifetime of 1.2 ns and 6 µm diffusion length at room temperature [24].…”

Section: Introductionmentioning

confidence: 99%

Broken edge spin symmetry induces a spin-polarized current in graphene nanoribbon

Ali,

Ali

2024

J. Phys. D: Appl. Phys.

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Zig-zag graphene nanoribbons (ZGNRs) are known to possess spin moments at the hydrogen-terminated edge carbon atoms, thus the spin-polarized electron transmission is expected while the current is longitudinally passed through the ZGNRs. However, in pristine ZGNRs, the spin-polarized transmission is not observed due to symmetric anti-parallel distributions of the spin densities between the edges. Here, the hypothesis is, any physical or chemical process that breaks such anti-parallel spin-symmetry can induce spin-polarized transmission in the ZGNRs. In this work, we have established this proof-of-concept by depositing the trimethylenemethane (TMM) radical on 6ZGNRH and investigating the quantum transport properties by employing the density functional theory in conjunction with nonequilibrium Green’s function (DFT-NEGF) method. Although TMM has a high magnetic moment (2 µB ), it does not induce magnetization in 6ZGNRH when TMM is physisorbed. But, during the chemisorption of TMM, it forms the π − π bond with the 6ZGNRH in a particular geometric configuration where the pz orbitals of carbon atoms of TMM have maximum overlap with the pz orbitals of carbon atoms of 6ZGNRH. The chemisorption of TMM transfers the spin moment to 6ZGNRH, which breaks the edge spin-symmetry of pristine 6ZGNRH. The adsorption of TMM radical results in transmission dips in the transmission spectra due to interference between localized states of TMM and 6ZGNRH states. This induces spin-polarized transmission with 60% spin-filtering efficiency (SFE) at zero bias, which can further be enhanced up to 92% by applying the bias voltage of 1.0 V.

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Single‐Molecule Cross‐Plane Conductance of Polycyclic Aromatic Hydrocarbon Derivatives

Yang,

Albalawi,

Zhao

et al. 2024

Chemistry A European J

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In the cross‐plane single‐molecule junctions, the correlation between molecular aromaticity and conductance remained puzzling. Cross‐plane break junction (XPBJ) provides new insight into understanding the role of aromaticity and conjugation to molecules on charge transport through the planar molecules. In this work, we investigated the modulation of cross‐plane charge transport in pyrene derivatives by hydrogenation and substituents based on the XPBJ method that differs from those used in‐plane transport. We measured the electrical conductance of the hydrogenated derivatives of the pyrenes and found that hydrogenation reduces conductance, and the fully hydrogenated molecule has the lowest conductance. Conductance of pyrene derivatives increased after substitution by both electron‐donating and electron‐withdrawing groups. By calculating, the trend in decreased conductance of hydrogenated pyrene was found to be consistent with the change in aromaticity. Electron‐withdrawing substituents reduce the aromaticity of the molecule and narrow the HOMO‐LUMO gap, while electron‐donating groups increase the aromaticity but also narrow the gap. Our work reveals the potential of fine‐tuning the structure of the pyrene molecule to control the cross‐plane charge transport through the single‐molecule junctions.

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Atomically well-defined nitrogen doping for cross-plane transport through graphene heterojunctions

Abstract: The nitrogen doping of graphene leads to graphene heterojunctions with a tunable bandgap, suitable for electronics, electrochemical, and sensing applications. However, the microscopic nature and charge transport properties of atomic-level...

Cited by 5 publications

References 62 publications

Synthesis and Properties of Diindeno[1,2,3‐cd:1′,2′,3′‐mn]pyrene and Two of Its Aza‐Analogs

Synthesis and Properties of Diindeno[1,2,3‐cd:1′,2′,3′‐mn]pyrene and Two of Its Aza‐Analogs

Broken edge spin symmetry induces a spin-polarized current in graphene nanoribbon

Single‐Molecule Cross‐Plane Conductance of Polycyclic Aromatic Hydrocarbon Derivatives

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