Ultrathin Organic Films Grown by Organic Molecular Beam Deposition and Related Techniques

Forrest, Stephen R.

doi:10.1021/cr941014o

Cited by 1,802 publications

(1,343 citation statements)

References 397 publications

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“…[1][2][3] Many of these applications rely on the formation of thin films of ordered structures of porphyrins and related compounds. [4][5][6][7] Intermolecular interactions such as dipole-dipole, 8 hydrogen bonding, 8 and coordination 9 in porphyrin building blocks are being used to create selfassembled structures on surfaces with increasing sophistication.…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Electrochemical Activity: An In Situ Electrochemical Scanning Tunneling Microscopy Study of Electrode Reactions and Potential-Induced Adsorption of Porphyrins

Borguet

2006

J. Phys. Chem. B

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The effect of adsorption on molecular properties and reactivity is a central topic in interfacial physical chemistry. At electrochemical interfaces, adsorbed molecules may lose their electrochemical activity. The absence of in situ probes has hindered our understanding of this phenomenon and electrode reactions in general. In this work, classical electrochemistry and electrochemical scanning tunneling microscopy (EC-STM) were combined to provide molecular level insight into electrochemical reactions and the molecular adsorption state at the electrolyte-electrode interface. The metal-free porphyrin 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (TPyP) adsorbed on Au(111) in 0.1 M H 2 SO 4 solution was chosen as a model system. TPyP is found to irreversibly adsorb on Au(111) over a wide range of potentials, from -0.25 to 0.6 V SCE . The adsorption state of TPyP has a dramatic effect on its electrochemistry. Preadsorbed, oxidized TPyP displays no well-defined cathodic peaks in cyclic voltammograms in sharp contrast to solution-phase TPyP. Our present work provides direct, molecular level evidence of the electrochemically "invisible" species. Electrochemical activity of absorbed species is recovered by allowing the oxidized molecule sufficient time (tens of minutes) to reduce. The redox state of adsorbed TPyP also affects the nature of the adsorption. Oxidized species can apparently only form monolayers. However, multilayers, stable enough to be imaged by STM, can form when the adsorbed TPyP is in the reduced state. This suggests that by controlling the electrochemistry one can either promote or suppress the formation of multilayers.

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Section: Introductionmentioning

confidence: 99%

Adsorption and Electrochemical Activity: An In Situ Electrochemical Scanning Tunneling Microscopy Study of Electrode Reactions and Potential-Induced Adsorption of Porphyrins

Borguet

2006

J. Phys. Chem. B

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“…9,10 Two different crystalline modifications, ␣-and ␤-phase, are known. [11][12][13][14] For both phases, the molecules in a PTCDA crystal form stacks that are parallel to the a-direction in the crystal, which is the direction of growth of needle-like PTCDA crystallites.…”

Section: Introductionmentioning

confidence: 99%

Exciton emission in PTCDA films andPTCDA∕Alq3multilayers

2004

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We investigate the exciton emission in 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) thin films and PTCDA/aluminium-tris-hydroxyqinoline ͑Alq 3 ͒ multilayers by photoluminescence spectroscopy in the temperature range from 10 to 300 K. The films are grown by organic molecular beam deposition on Si (001) and Pyrex™ substrates at high vacuum. The obtained temperature dependence of the different recombination channels arising from indirect Frenkel excitons, charge transfer excitons, excimers, and relaxed excited monomers is compared to the recombination channels in single PTCDA crystals. A strong recombination band is observed at 1.63 eV in PTCDA/ Alq 3 multilayers. This emission band is attributed to charge transfer transitions between stacked PTCDA molecules that are compressed by strain fields within the PTCDA layers. This assignment is supported by strain-dependent photoluminescence measurements on pure PTCDA films.

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“…Due to the good electrondonating nature of triphenylamine (TPA), its polymers have been widely studied as hole-transporting materials for a number of applications, such as xerography, organic field-effect transistors, photorefractive systems, light-emitting diodes, etc. [11,12]. These interesting properties are associated with presence of a TPA moiety that contains the nitrogen center (the electroactive site) linked to three electron-rich phenyl groups in a propeller-like geometry [13].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Linear, Branched and Hyperbranched Triphenylamine-Based Polyazomethines

Grigoraş¹,

Stafie²

2009

Designed Monomers and Polymers

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Novel triphenylamine-based linear, hyperbranched and branched conjugated polyazomethines have been synthesized by free-catalyst solution polycondensation of 1,4-diaminobenzene with 4,4 -diformyl triphenylamine, 4,4 ,4 -triformyl triphenylamine and their mixture in different molar ratios. Linear polyazomethine has a good solubility in organic solvents while branched and hyperbranched polymers are partially soluble. A wholly soluble hyperbranched polyazomethine was obtained by end-capping of polymer at gelation point using a monofunctional aromatic amine, p-anisidine. Characterization of all polymers was made by 1 H-NMR, FT-IR and UV-Vis and photoluminescence spectroscopy and thermal methods. Electrochemical behavior of polymers was studied by cyclic voltammetry using thin films cast from THF solution on a platinum disc working electrode in acetonitrile solvent and tetrabutylammonium tetrafluoroborate as electrolyte.

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Ultrathin Organic Films Grown by Organic Molecular Beam Deposition and Related Techniques

Cited by 1,802 publications

References 397 publications

Adsorption and Electrochemical Activity: An In Situ Electrochemical Scanning Tunneling Microscopy Study of Electrode Reactions and Potential-Induced Adsorption of Porphyrins

Adsorption and Electrochemical Activity: An In Situ Electrochemical Scanning Tunneling Microscopy Study of Electrode Reactions and Potential-Induced Adsorption of Porphyrins

Exciton emission in PTCDA films andPTCDA∕Alq3multilayers

Synthesis and Characterization of Linear, Branched and Hyperbranched Triphenylamine-Based Polyazomethines

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