Metallic conduction at organic charge-transfer interfaces

Alves, Helena; Molinari, Anna; Xie, Hangxing; Morpurgo, Alberto F.

doi:10.1038/nmat2205

Cited by 373 publications

(344 citation statements)

References 39 publications

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“…Several studies have addressed the properties of surface-supported structures involving TCNQ, where charge-transfer likewise must play a prominent role. Alves et al observed metallic conductivity within a single stacked interface of TTF and TCNQ [7]. Studies of TCNQ based salts on Au(111) surface have shown supermolecular states along the 1D TCNQ chains dependent on the geometry of neighboring molecules and hybridization with the underlying metal substrate [8].…”

Section: Introductionmentioning

confidence: 99%

Weak competing interactions control assembly of strongly bonded TCNQ ionic acceptor molecules on silver surfaces

et al. 2014

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The energy scale of interactions that control molecular adsorption and assembly on surfaces can vary by several orders of magnitude, yet the importance of each contributing interaction is not apparent a-priori.Tetracyanoquinodimethane (TCNQ) is an archetypal electron acceptor molecule and it is a key component of organic metals. On metal surfaces, this molecule also acts as an electron acceptor, producing negatively charged adsorbates. It is therefore rather intriguing to observe attractive molecular interactions in this system that was reported previously for copper and silver surfaces. Our experiments compared TCNQ adsorption on noble metal surfaces of Ag(100) and Ag(111). In both cases we found net attractive interactions down to the lowest coverage. However, the morphology of the assemblies was strikingly different, with 2D islands on Ag(100) and 1D chains on Ag(111) surfaces. This observation suggests that the registry effect governed by the molecular interaction with the underlying lattice potential is critical in determining the dimensionality of the molecular assembly. Using first-principles 2 density functional calculations with van der Waals correction scheme, we revealed that the strengths of major interactions (i.e., lattice potential corrugation, intermolecular attraction, and charge transferinduced repulsion) are all similar in energy. Van der Waals interactions, in particular, almost double the strength of attractive interactions, making the intermolecular potential comparable in strength to the diffusion potential and promoting self-assembly. However, it is the anisotropy of local intermolecular interactions that is primarily responsible for the difference in the topology of the molecular islands on Ag(100) and Ag(111) surfaces. We anticipate that the intermolecular potential will become more attractive and dominant over the diffusion potential with increasing molecular size, providing new design strategies for the structure and charge-transfer within molecular layers.

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Section: Introductionmentioning

confidence: 99%

Weak competing interactions control assembly of strongly bonded TCNQ ionic acceptor molecules on silver surfaces

et al. 2014

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“…Organic electroluminescent displays and organic solar cells are already commercially available. Interfacial charge transfer makes the interface of two insulating organic crystals conductive 2 . In spintronics, organic semiconductors are regarded as attractive materials for use in spin valve devices because of their ability to maintain the spin polarization of the carriers 3 .…”

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confidence: 99%

Large surface relaxation in the organic semiconductor tetracene

et al. 2014

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Organic crystals are likely to have a large degree of structural relaxation near their surfaces because of the weak inter-molecular interactions. The design of organic field-effect transistors requires a detailed knowledge of the surface relaxation as the carriers usually transfer within the first few molecular layers at the semiconductor surfaces, and their transport properties reflect the structural changes through the transfer integral. Here, we report the direct observation of the surface relaxation of an organic semiconductor, a tetracene single crystal, by means of X-ray crystal truncation rod scattering measurements. A significant degree of surface relaxation is observed, taking place only in the first monolayer at the semiconductor surface. First principles calculations show that the resultant transfer integrals are completely different between the bulk and surface of the semiconductor.

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“…Such interfaces can display remarkable properties both in inorganic 7 and organic materials. Recently, Alves et al 8 have demonstrated that metallicity can arise at the interface of two organic insulators. Here, we show that this method can also be used to significantly increase the conductivity in hybrid materials.…”

mentioning

confidence: 99%

“…Alves et al 8 already showed that charge transfer at the interface between a TTF and a TCNQ crystal can generate up to two orders of magnitude more mobile charge carriers than in FETs. Similarly, the thin film of the electron donating insulator TTF on top of the CuCl 4 -hybrid crystal introduces charge transfer at the TTFhybrid interface that increases the conductance by five orders of magnitude.…”

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confidence: 99%

Charge-transfer induced surface conductivity for a copper based inorganic-organic hybrid

Arkenbout¹,

Uemura

Takeya

et al. 2009

Applied Physics Letters

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Inorganic-organic hybrids are receiving increasing attention as they offer the opportunity to combine the robust properties of inorganic materials with the versatility of organic compounds. We have studied the electric properties of an inorganic-organic hybrid with the chemical formula: CuCl4(C6H5CH2CH2NH3)2. This material is a ferromagnetic insulator that can easily be processed from solution. We show that the surface conductivity of the hybrid can be increased by five orders of magnitude by covering the surface with an organic electron donor. This constitutes a novel method to dope perovskite-based materials and study their charge transport properties.

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Metallic conduction at organic charge-transfer interfaces

Cited by 373 publications

References 39 publications

Weak competing interactions control assembly of strongly bonded TCNQ ionic acceptor molecules on silver surfaces

Weak competing interactions control assembly of strongly bonded TCNQ ionic acceptor molecules on silver surfaces

Large surface relaxation in the organic semiconductor tetracene

Charge-transfer induced surface conductivity for a copper based inorganic-organic hybrid

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