Free-Energy-Driven Transfer of Charge in Dense Electrochemically Active Monomolecular Films

Zaslavsky, Dmitry; Pakoulev, Andrei V.; Burtman, Vladimir

doi:10.1021/jp047315b

Cited by 7 publications

(3 citation statements)

References 30 publications

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“…For most applications, deposition of the NDI as thin films is required. Early work employed gas phase deposition techniques, such as chemical vapor deposition. − Those techniques, however, are highly energy intensive, and hence solution processability has become an important goal, especially green methods employing aqueous media at room temperature. Among the most common solution methods that have been used for NDI deposition as thin films are spin-coating, − dip-coating, − and Langmuir–Blodgett .…”

Section: Introductionmentioning

confidence: 99%

Radical Anions and Dianions of Naphthalenediimides Generated within Layer-by-Layer Zirconium Phosphonate Thin Films

2022

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Chemical reduction of N,N′-bis(2-phosphonoethyl)-1,4,5,8naphthalenediimide (PNDI) with the reducing agent sodium dithionite gave stable colored reduced species, both in homogeneous solutions and in selfassembled thin films. When colorless PNDI aqueous solutions were titrated with the reducing agent, stepwise reduction was observed, giving first the radical anion (PNDI −• ) and then the dianion (PNDI 2− ) species, which were detected by UV−visible−NIR spectroscopy, allowing the unambiguous determination of absorption maxima and molar absorptivities for each species. The radical anion PNDI −• was found to form π-dimers in water, but monomeric PNDI −• was formed in the presence of the cationic surfactant cetyltrimethylammonium bromide, indicating association with the micelles. Thin films of PNDI with 25 layers were grown by the zirconium phosphonate method on quartz substrates. Reduction of the films with sodium dithionite also produced radical anions and dianions of PNDI. However, reduction in the films was much slower than in solution, evidencing the compactness of the films. Moreover, reduction in the films did not proceed to completion, even with excess of the reducing agent, which can be attributed to the repulsion of negative charges within the film.

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Section: Introductionmentioning

confidence: 99%

Radical Anions and Dianions of Naphthalenediimides Generated within Layer-by-Layer Zirconium Phosphonate Thin Films

2022

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“…Such molecules were dubbed "molecular wires" due to the low value of the -electron wave function decay constant, ␤, which is associated with large intramolecular electron conductance along the molecular principal axis. 11,12 Other ordered organic molecular systems also show delocalization perpendicular to the principal direction, but these are not strictly 2D. Currently, the most popular approaches of fabricating such 1D molecular diodes are mechanical break junctions, 2 electromigration break junctions, 3 films in nanopores, 4 nanoparticle bridged junctions, 5,6 and a broad range of devices in which scanning tunneling microscopy ͑STM͒ or atomic force microscopy ͑AFM͒ tips serve as the upper electrode.…”

Section: Introductionmentioning

confidence: 99%

Electrical and optical studies of gap states in self-assembled molecular aggregates

Burtman

Hukic

Ndobe

et al. 2007

Journal of Applied Physics

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Articles you may be interested inMolecular self ordering and charge transport in layer by layer deposited poly (3,3-dialkylquarterthiophene) films formed by Langmuir-Schaefer technique J. Appl. Phys. 116, 094311 (2014); 10.1063/1.4894515 Molecular and electronic structure of electroactive self-assembled monolayers Structure and optical properties of self-assembled multicomponent plasmonic nanogels Appl. Phys. Lett. 99, 043112 (2011); 10.1063/1.3615785 Energy level alignment at organic semiconductor/metal interfaces: Effect of polar self-assembled monolayers at the interface J. Chem. Phys. 128, 074705 (2008); 10.1063/1.2832306Conformations and charge transport characteristics of biphenyldithiol self-assembled-monolayer molecular electronic devices: A multiscale computational studyWe fabricated a variety of two-terminal devices using self-assembled monolayers ͑SAM͒ of solid-state mixtures comprised of molecular "wires" ͓1,4-methane-benzenedithiol ͑Me-BDT͔͒ and molecular insulator "spacers" ͓1-pentanethiol͔, which were prepared at various molar concentrations ratio, r of wires/spacers, and sandwiched between two gold electrodes. The devices' electrical transport was investigated at several r values using the bias voltage ͑V͒ dependencies of the conductance and differential conductance at various temperatures. In parallel, we also studied the UV-visible absorption and photoluminescence ͑PL͒ emission spectra of the SAM mixtures grown on silica transparent substrates. For r Ͼ 10 −3 we found that two-dimensional ͑2D͒ Me-BDT aggregates are formed in the SAM films leading to novel properties compared to SAM films of isolated Me-BDT molecules at concentrations 10 −8 Ͻr Ͻ 10 −4 , which we studied before ͓V. Burtman, A. S. Ndobe, and Z. V. Vardeny, J. Appl. Phys. 98, 034314 ͑2005͔͒. First, an Ohmic response in the current-voltage ͑I-V͒ characteristics is obtained up to V ϳ 0.5 V, which results in a new band in the differential conductance spectrum around V = 0. Second, a new subgap absorption band is formed at ϳ2.4 eV, which is related to a new yellow/red PL emission band. The novel optical and electrical properties of the 2D Me-BDT aggregates are explained by the formation of an electronic continuum band in the Me-BDT energy gap, which is caused by weak in-plane charge delocalization among the molecules forming the aggregates. To verify this model we also studied SAM molecular aggregate diodes using Al electrodes. The 1-eV difference in the electrode work function between Au and Al metals results in a pronounced E F shift with respect to the aggregate-related continuum band in the gap, and consequently, dramatically changes the device I-V characteristics.

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“…1 Much progress has been made on understanding electronic processes such as molecular charge transport in organic thin films. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Several methods, including shear force-based scanning probe microscopy (SPM), 4 atomic force electrochemical microscopy (AFM-SECM), 11 and cyclic voltammetry using mercury contact electrodes 2,3,6 have been used to study the abovementioned phenomena. Until now, fundamental questions such as the distribution of injected charge within organic thin films are difficult to address.…”

mentioning

confidence: 99%

Site Affinity Effects upon Charge Injection into Siloxane-based Monolayers

et al. 2006

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Submolecular electrical information is successfully derived by applying element-specific, chemically resolved electrical measurements to a covalently bound stilbazole-based monolayer on a silicon substrate. Pronounced affinity effects are found in the response of adjacent atomic sites to external charge injection, accompanied by intramolecular polarization variations. These noncontact electrical read-out capabilities may provide a first entry toward the realization of organic devices based on submolecular electrical units.

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Free-Energy-Driven Transfer of Charge in Dense Electrochemically Active Monomolecular Films

Abstract: Classification: Physical Sciences, Chemistry.

Cited by 7 publications

References 30 publications

Radical Anions and Dianions of Naphthalenediimides Generated within Layer-by-Layer Zirconium Phosphonate Thin Films

Radical Anions and Dianions of Naphthalenediimides Generated within Layer-by-Layer Zirconium Phosphonate Thin Films

Electrical and optical studies of gap states in self-assembled molecular aggregates

Site Affinity Effects upon Charge Injection into Siloxane-based Monolayers

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