Phenylphosphonic Acid Functionalization of Indium Tin Oxide:  Surface Chemistry and Work Functions

Koh, Sharon E; McDonald, Krystal D; Holt, David H.; Dulcey, C. S.; Chaney, John A.; Pehrsson, Pehr E.

doi:10.1021/la052379e

Cited by 85 publications

(134 citation statements)

References 43 publications

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“…This concept has been extensively studied and reported in the previous publications [36][37][38][39][40]. Charge transfer from the COOH head group of MPPBA molecule to ITO surface leads to the formation of C-O bond due to electrostatic interaction between positively charged ITO surface and the delocalized electrons in the oxygen atom of carboxylate group in MPPBA molecule [41].…”

Section: Effect Of Molecular Dipole On Ito Work Functionmentioning

confidence: 99%

Modification of ITO surface using aromatic small molecules with carboxylic acid groups for OLED applications

et al. 2011

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a b s t r a c t 4-[(3-Methylphenyl)(phenyl)amino]benzoic acid (MPPBA) was synthesized in order to facilitate the hole-injection in Organic Light Emitting Diodes (OLED). MPPBA was applied to form self-assembled monolayer (SAM) on indium tin oxide (ITO) anode to align energy-level at the interface between organic semiconductor material (TPD) and inorganic anode (ITO) in OLED devices. The modified surface was characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). KPFM was used to measure the surface potential and work function between the tip and the ITO surface modified by SAM technique using MPPBA. The OLED devices (ITO/MPPBA/TPD/Alq 3 /Al) fabricated with SAM-modified ITO substrates showed lower turn-on voltages and enhanced diode current compare to the OLED devices fabricated with bare ITO substrates.Crown

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Section: Effect Of Molecular Dipole On Ito Work Functionmentioning

confidence: 99%

Modification of ITO surface using aromatic small molecules with carboxylic acid groups for OLED applications

et al. 2011

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“…Trialkoxysilanes are widely used surface modifiers for silicate, indium tin oxide, and other metal oxide surfaces. Phosphonic acids have been reported to modify TiO 2 , ZrO 2 , and indium tin oxide surfaces [18][19][20] and are thought to couple to the surface of metal oxides either by heterocondensation with surface hydroxyl groups or coordination to metal ions on the surface.[18] Carboxylic acid and sulfonic acid groups may also bind to the surface in a similar manner. A sample of each ligand was mixed with BT nanoparticles (30-50 nm, 0.5 mmol ligand/ g BT) in an ethanol/water solution and stirred at 80°C, followed by extensive washing with ethanol or water and centrifugation to remove excess and/or physisorbed ligand.…”

mentioning

confidence: 99%

Phosphonic Acid‐Modified Barium Titanate Polymer Nanocomposites with High Permittivity and Dielectric Strength

et al. 2007

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Materials with high dielectric permittivity are important in electronic components such as capacitors, gate dielectrics, memories, and power-storage devices. [1][2][3][4] Conventional highpermittivity materials such as barium titanate (BT) can be processed into thin films by using chemical solution deposition yielding a relative permittivity (e r ) of about 2500 and relatively low dielectric loss but require high-temperature sintering, which is not compatible with many substrate materials.[ [7][8][9][10] Polymer/ceramic nanocomposites in which high-e r metal oxide nanoparticles such as BT [11,12] and lead magnesium niobate-lead titanate (PMN-PT) [1,13,14] are incorporated into a polymer host are of significant current interest. The combination of high-e r nanoparticles with high-dielectric-strength polymer hosts offers the potential to obtain processable highperformance dielectric materials. Simple solution processing of BT particles in a polymer host generally results in poor film quality and inhomogeneities, which are mainly caused by agglomeration of the nanoparticles. Addition of surfactants, such as phosphate esters and oligomers thereof, can improve the dispersion of BT nanoparticles in host polymers and consequently the overall nanocomposite film quality. [1,13,15] However, in such systems, residual free surfactant can lead to high leakage current and dielectric loss. [16] Thus, approaches to bind surface modifiers to BT nanoparticles via robust chemical bonds are highly desirable. Ramesh et al. have reported on the use of trialkoxysilane surface modifiers for the dispersion of BT nanoparticles in epoxy polymer hosts resulting in nanocomposites with reasonably high e r , up to 45. [12] With the objective of identifying ligands that can form stable bonds to a BT surface through coordination or condensation, we have investigated a series of different ligand functionalities. In this Communication, we report that phosphonic acid ligands effect robust surface modification of BT and related nanoparticles and that the use of particles modified with suitable phosphonic acid ligands leads to well-dispersed BT nanocomposite films with high e r and high dielectric strength.We have investigated the binding of a variety of ligands to the surface of BT nanoparticles, as the stability of the binding on the surface is vital to effective surface modification.[17] We examined the following set of ligands, each bearing an aliphatic octyl chain with a different terminal binding group: C 8 H 17 -X, where X = PO(OH) 2 (OPA), SO 2 ONa (OSA), Si(OCH 3 ) 3 (OTMOS), and CO 2 H (OCA). Trialkoxysilanes are widely used surface modifiers for silicate, indium tin oxide, and other metal oxide surfaces. Phosphonic acids have been reported to modify TiO 2 , ZrO 2 , and indium tin oxide surfaces [18][19][20] and are thought to couple to the surface of metal oxides either by heterocondensation with surface hydroxyl groups or coordination to metal ions on the surface.[18] Carboxylic acid and sulfonic acid groups may also bind to the surface ...

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“…[1][2][3][4] Like other organic electronic devices, [5][6][7] charge injection at the organicinorganic interface is a key issue for OPVs. 8,9 Surface treatments of electrode including oxidation, the addition of a selfassembled layer, [10][11][12][13][14] or poly͑3,4-ethylene dioxythiophene͒: poly͑styrene-sulfonate͒ ͑PEDOT:PSS͒ layer insertion 15 can lower or raise the work functions of cathodes and anodes, or enhance the cohesion, and thus lower the interfacial series resistance. However, the effects on OPV device performance of shifting the electrode's work function and altering the active layer's structure that result from changing the surface energy of the indium tin otide ͑ITO͒ electrode have not previously been reported.…”

mentioning

confidence: 99%

Control of the electrode work function and active layer morphology via surface modification of indium tin oxide for high efficiency organic photovoltaics

Kim

Park

Lee

et al. 2007

Applied Physics Letters

226

137

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Phenylphosphonic Acid Functionalization of Indium Tin Oxide: Surface Chemistry and Work Functions

Cited by 85 publications

References 43 publications

Modification of ITO surface using aromatic small molecules with carboxylic acid groups for OLED applications

Modification of ITO surface using aromatic small molecules with carboxylic acid groups for OLED applications

Phosphonic Acid‐Modified Barium Titanate Polymer Nanocomposites with High Permittivity and Dielectric Strength

Control of the electrode work function and active layer morphology via surface modification of indium tin oxide for high efficiency organic photovoltaics

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