Advanced Surface Modification of Indium Tin Oxide for Improved Charge Injection in Organic Devices

Hanson, Eric L.; Guo, Jing; Koch, Norbert; Schwartz, Jeffrey; Bernasek, Steven L.

doi:10.1021/ja050481s

Cited by 184 publications

(206 citation statements)

References 35 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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“…Transparent conductive oxides (TCOs) are essential electrode materials for applications in organic electronics, such as organic photovoltaics (OPVs), [1][2][3][4] organic thin-film transistors, 5 organic light-emitting diodes, 6,7 and perovskite solar cells. 8 Understanding and controlling the surface properties of TCO electrodes can improve the performance of these types of devices.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, PDI redox potentials can be tuned, most effectively through substitutions at the "bay" (1,6,7,12) and/or "ortho" (2,5,8,11) positions, allowing them to be energetically matched to different active-layer and TCO materials. 25,26 In a recent study, 27 we began examining the properties of PDI monolayers tethered to ITO via phosphonic acid (PA) anchoring groups.…”

Section: Introductionmentioning

confidence: 99%

Influence of Molecular Aggregation on Electron Transfer at the Perylene Diimide/Indium-Tin Oxide Interface

Zheng

Jradi

Parker

et al. 2016

ACS Appl. Mater. Interfaces

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Chemisorption of an organic monolayer to tune the surface properties of a transparent conductive oxide (TCO) electrode can improve the performance of organic electronic devices that rely on efficient charge transfer between an organic active layer and a TCO contact. Here a series of perylene diimides (PDIs) was synthesized and used to study relationships between monolayer structure/properties and electron transfer kinetics at PDI-modified indium tin oxide (ITO) electrodes. In these PDI molecules, one of the imide substituents is a benzene ring bearing a phosphonic acid (PA) and the other is a bulky aryl group that is twisted out of the plane of the PDI core. The size of the bulky aryl group and the substitution of the benzene ring bearing the PA were both varied which altered the extent of aggregation when these molecules were absorbed as monolayer films (MLs) on ITO, as revealed by both attenuated total reflectance (ATR) and total internal reflection fluorescence (TIRF) spectra. Polarized ATR measurements indicate that in these MLs, the long axis of the PDI core is tilted at an angle of 33˚-42˚ relative to the surface normal; the tilt angle increased as the degree of bulky substitution increased. Rate constants for electron transfer (k s,opt ) between these redox-active modifiers and ITO were determined by potential-modulated ATR spectroscopy. As the degree of PDI aggregation was reduced, k s,opt declined which is attributed to a reduction in the lateral electron self-exchange rate between adsorbed PDI molecules, as well as the heterogeneous conductivity of the ITO electrode surface. Photoelectrochemical measurements using a dissolved aluminum phthalocyanine as an electron donor showed that ITO modified with any of these PDIs is a more effective electron-collecting electrode than bare ITO.

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“…This work is based on the idea that this could eventually be achieved by inserting a self-assembled monolayer, i.e, a structure that is self-fabricated upon deposition, and could also modify the metal electrode's work-function and the charge carrier injection barrier, e.g., in an organic field effect transistor. 17 Recently, charge transfer complexes have been used in this context, 18,19 showing interesting effects on hole-injection barriers. More generally, self-assembly can lead to the formation of a wide range of twodimensional structures with different mechanical and electrostatic properties 20À22 and appears to be a very promising route for the nanofabrication of interlayers.…”

mentioning

confidence: 99%

Fine-Tuning the Electrostatic Properties of an Alkali-Linked Organic Adlayer on a Metal Substrate

2013

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The performance of modern organic electronic devices is often determined by the electronic level alignment at a metal–organic interface. This property can be controlled by introducing an interfacial electrostatic dipole via the insertion of a stable interlayer between the metallic and the organic phases. Here, we use density functional theory to investigate the electrostatic properties of an assembled structure formed by alkali metals coadsorbed with 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecules on a Ag(100) substrate. We find that the interfacial dipole buildup is regulated by the interplay of adsorption energetics, steric constraints and charge transfer effects, so that choosing chemical substitutions within TCNQ and different alkali metals provides a rich playground to control the systems’ electrostatics and in particular fine-tune its work-function shift

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Advanced Surface Modification of Indium Tin Oxide for Improved Charge Injection in Organic Devices

Cited by 184 publications

References 35 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

Influence of Molecular Aggregation on Electron Transfer at the Perylene Diimide/Indium-Tin Oxide Interface

Fine-Tuning the Electrostatic Properties of an Alkali-Linked Organic Adlayer on a Metal Substrate

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