<scp><i>N</i>‐Heterocyclic</scp> Carbene Anchors in Electronics Applications

Kang, Shin-Jin; Byeon, Seo Eun; Yoon, Ho‐Geun

doi:10.1002/bkcs.12261

Cited by 26 publications

(25 citation statements)

References 47 publications

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“…Furthermore, because of their stability, the derivatizations of the NHC-SAMs are achieved by simple aromatic substitution and S N 2 chemistry in situ, which enables the installation of functional groups such as ferrocene and dextran for biosensing. 234 Recently Kang and colleagues 29,235 Thermoelectric characterization of the junctions shows the dependence of thermopower on the molecular length and a positive Seebeck coefficient [Fig. 9(e)], which confirms that tunneling transport is hole assisted, i.e., the HOMO is closer to E f than the LUMO.…”

Section: Emerging Anchoring Chemistrymentioning

confidence: 80%

“…[24][25][26] These systems are better described as more or less Landauer-like and Marcus-like, as activationless, incoherent processes become possible that are not well described by the tunneling/ hopping dichotomy. [27][28][29] The most commonly used theoretical model to describe temperature-independent tunneling is the simplified Simmons model, [30][31][32] which considers the junction formed by the molecule as an approximately trapezoidal potential barrier and is mathematically described by Eq. 1 where J is the current density; V is the applied bias; d is the zero-bias width of the barrier, which is nominally determined by molecular length; b is the tunneling decay coefficient and scales with the square root of the difference between the Fermi level E f and the frontier orbitals of the molecule(s); and J 0 is the theoretical value of J when d ¼ 0.…”

Section: A Mechanisms Of Charge Transportmentioning

confidence: 99%

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Charge transport through molecular ensembles: Recent progress in molecular electronics

Liu¹,

Soni

Qiu³

et al. 2021

Chemical Physics Reviews

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This review focuses on molecular ensemble junctions in which the individual molecules of a monolayer each span two electrodes. This geometry favors quantum mechanical tunneling as the dominant mechanism of charge transport, which translates perturbances on the scale of bond lengths into nonlinear electrical responses. The ability to affect these responses at low voltages and with a variety of inputs, such as de/protonation, photon absorption, isomerization, oxidation/reduction, etc., creates the possibility to fabricate molecule-scale electronic devices that augment; extend; and, in some cases, outperform conventional semiconductor-based electronics. Moreover, these molecular devices, in part, fabricate themselves by defining single-nanometer features with atomic precision via self-assembly. Although these junctions share many properties with single-molecule junctions, they also possess unique properties that present a different set of problems and exhibit unique properties. The primary trade-off of ensemble junctions is complexity for functionality; disordered molecular ensembles are significantly more difficult to model, particularly atomistically, but they are static and can be incorporated into integrated circuits. Progress toward useful functionality has accelerated in recent years, concomitant with deeper scientific insight into the mediation of charge transport by ensembles of molecules and experimental platforms that enable empirical studies to control for defects and artifacts. This review separates junctions by the trade-offs, complexity, and sensitivity of their constituents; the bottom electrode to which the ensembles are anchored and the nature of the anchoring chemistry both chemically and with respect to electronic coupling; the molecular layer and the relationship among electronic structure, mechanism of charge transport, and electrical output; and the top electrode that realizes an individual junction by defining its geometry and a second molecule-electrode interface. Due to growing interest in and accessibility of this interdisciplinary field, there is now sufficient variety in each of these parts to be able to treat them separately. When viewed this way, clear structure-function relationships emerge that can serve as design rules for extracting useful functionality.

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Section: Emerging Anchoring Chemistrymentioning

confidence: 80%

Section: A Mechanisms Of Charge Transportmentioning

confidence: 99%

Charge transport through molecular ensembles: Recent progress in molecular electronics

Liu¹,

Soni

Qiu³

et al. 2021

Chemical Physics Reviews

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“…N-heterocyclic carbene (NHC) ligands' strong metal-carbon bonds and highly tunable structures enable numerous applications, including organometallic catalysis, 1−3 electronics, 4 supramolecular chemistry, 5 metal−organic frameworks, 6 and medicinal chemistry. 7 To add to this considerable collection, NHCs were recently shown to form robust selfassembled monolayers (SAMs) 8−10 stable under electrochemical cycling, 11 high temperatures, 12−14 catalytic cycling, 15,16 and exposure to rigorous chemical environments, 17−20 signifying that they are an attractive alternative to the widely used, but labile, thiols in noble-metal surface functionalization.…”

mentioning

confidence: 99%

Probing N-Heterocyclic Carbene Surfaces with Laser Desorption Ionization Mass Spectrometry

et al. 2021

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The proliferation of N-heterocyclic carbene (NHC) self-assembled monolayers (SAMs) on gold surfaces stems from their exceptional stability compared to conventional thiol-SAMs. The prospect of biological applications for NHC-SAMs on gold shows the need for biocompatible techniques (e.g., large biomolecule detection and high throughput) that assesses SAM molecular composition. Herein, we demonstrate that laser desorption ionization mass spectrometry (LDI-MS) is a powerful and facile probe of NHC surface chemistry. LDI-MS of prototypical imidazole-NHC-and benzimidazole-NHC-functionalized AuNPs yields exclusively [NHC 2 Au] + ions and not larger gold clusters. Employing benzimidazole-NHC isotopologues, we explore how monolayers pack on a single AuNP and the lability of the NHCs once ligated. Quantitative analysis of the homoleptic and heteroleptic [NHC 2 Au] + ions is performed by comparing to a binomial model representative of a randomized monolayer. Lastly, the reduction of nitro-NHC-AuNPs to amine-NHC-AuNPs is tracked via LDI-MS signals, illustrating the ability of LDI-MS to probe postsynthetic modifications of the anchored NHCs, which is critical for current and future applications of NHC surfaces.

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“…[ 8k ] Fifth, the widely used thiol anchor has been employed for SAM‐based passivation. Given that thiol can be easily decomposed under ambient conditions, [ 42 ] a robust anchor such as N‐heterocyclic carbene [ 43 ] (Figure 12d) can be promising for realizing commercial PeLEDs. Sixth, phase transition can occur in red perovskites, which can deteriorate the PeLED performance.…”

Section: Concluding Remarks and Perspectivesmentioning

confidence: 99%

Small Molecule Approach to Passivate Undercoordinated Ions in Perovskite Light Emitting Diodes: Progress and Challenges

Lee

Kim

Yoon

2021

Advanced Optical Materials

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Perovskite light‐emitting diodes (PeLEDs) hold promise for the development of next‐generation display and light technologies; however, various problems related to factors such as external quantum efficiency (EQE), long‐term stability, and dependence on toxic species hinder their successful debut in display and lighting markets. Research on PeLEDs involving the small‐molecule approach—the incorporation of small organic molecules into or onto active perovskite layers in PeLEDs for mitigating the aforementioned issues—has burgeoned in the last eight years. This review covers recent advances and challenges in the small‐molecule approach by i) surveying the chemical structures used in the small‐molecule approach, ii) summarizing the methods of molecular insertion into PeLED devices, iii) comprehensively discussing the effects of small‐molecule‐based interfacial engineering and passivation of undercoordinated metal and halide ions on the photophysical functions of devices and their mechanisms, iv) emphasizing the small‐molecule‐induced enhanced performance of devices in the context of long‐term stability and EQE, and v) providing perspectives and discussing challenges for future research.

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N‐Heterocyclic Carbene Anchors in Electronics Applications

Cited by 26 publications

References 47 publications

Charge transport through molecular ensembles: Recent progress in molecular electronics

Charge transport through molecular ensembles: Recent progress in molecular electronics

Probing N-Heterocyclic Carbene Surfaces with Laser Desorption Ionization Mass Spectrometry

Small Molecule Approach to Passivate Undercoordinated Ions in Perovskite Light Emitting Diodes: Progress and Challenges

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