Ultrathin Self-Assembled Layers at the ITO Interface to Control Charge Injection and Electroluminescence Efficiency in Polymer Light-Emitting Diodes

Ho, Peter K. H.; Granström, Magnus; Friend, Richard H.

doi:10.1002/(sici)1521-4095(199807)10:10<769::aid-adma769>3.3.co;2-v

Cited by 65 publications

(87 citation statements)

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“…The electric-field-dependent mobility of holes in PFB has been previously measured by time-of-flight and dark-injection SCL transient current methods [14,17] and room-temperature values of l 0 and c have been obtained: l 0 = 5 10 ±5 cm 2 V ±1 s ±1 and c = 3.1 10 ±3 (cm V ±1 ) 1/2 . By setting V BI~1 V and e~3 the SCL current density can then be calculated as a function of voltage for d = 400 nm.…”

Section: Resultsmentioning

confidence: 99%

“…[8±12] In PLEDs however, the use of PEDOT:PSS is much more common and there have been only a few attempts at incorporating SAMs at the ITO/polymer interface in order to improve the hole injection process. [7,13,14] In this paper we show how different organic molecules, possessing a range of dipole moments, can be used to tune hole injection in PLEDs based on a model polyfluorene copolymer poly(9,9-dioctylfluorene-co-bis-N,N¢-4-butylphenyl)-bis-N,N¢-phenyl-1,4-phenylenediamine) (PFB). This polymer possesses a relatively high non-dispersive hole mobility of over 10 ±4 cm 2 V ±1 s ±1 [15] and a relatively low ionization potential of 5.09 eV.…”

Section: Full Papermentioning

confidence: 99%

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Using Self‐Assembling Dipole Molecules to Improve Hole Injection in Conjugated Polymers

Khodabakhsh

Poplavskyy²,

Heutz

et al. 2004

Adv Funct Materials

155

117

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Surface modification of indium‐tin‐oxide (ITO)‐coated substrates through the use of self‐assembled monolayers (SAMs) of molecules with permanent dipole moments has been used to control the ITO work function and device performance in polymer light‐emitting diodes based on a polyfluorene hole transporting copolymer. Measured current–voltage characteristics of the devices reveal greatly increased hole injection currents from the SAM‐altered electrodes with higher work function, in agreement with an expected reduction in the barrier for hole injection. In particular, it is shown that the SAM‐modified electrode with the highest work function provides an ohmic contact for hole injection into the studied polymer. Injection from the widely used poly(2,3‐ethylenedioxythiophene)/polystyrenesulphonic acid (PEDOT:PSS)‐coated ITO anode system, is less efficient compared with some of the studied SAM‐coated ITO anodes despite the significantly higher work function measured by a Kelvin probe. This apparently anomalous situation is attributed to the inhomogenities in the injection processes that occur over the area of the device when the PEDOT:PSS‐coated ITO electrode is used.

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Section: Resultsmentioning

confidence: 99%

Section: Full Papermentioning

confidence: 99%

Using Self‐Assembling Dipole Molecules to Improve Hole Injection in Conjugated Polymers

Khodabakhsh

Poplavskyy²,

Heutz

et al. 2004

Adv Funct Materials

155

117

View full text Add to dashboard Cite

show abstract

“…There is still some debate as to whether the enhancement in device performance is due to enhancements in wettability of the oxide surface toward the nonpolar molecules used in these devices, to changes in work function of the oxide surface, and/or to enhancements in intrinsic rates of charge injection [7][8][9][10][11][12][13]. Many of the same strategies initially used to enhance solution electron transfer rates on these oxide surfaces appear to positively impact device efficiencies in simple OLEDs and OPVs [9,[14][15][16][17][18]]. …”

Section: The Metal Oxide Electrode and Modification Schemesmentioning

confidence: 99%

Modification of Transparent Conducting Oxide ( TCO ) Electrodes through Silanization and Chemisorption of Small Molecules

Brumbach

Armstrong

2007

Encyclopedia of Electrochemistry

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The sections in this article are Introduction The Metal Oxide Electrode and Modification Schemes Commonly Encountered TCO Electrodes Variability in TCO Electrodes Factors that Control the Surface Composition of the TCO Electrode Chemical Modification of TCO Surfaces Using Silane Chemistries Introduction to Silane Modification Examples of Silane Modification Silane Modification of Electrodes for Use in Devices Modification of TCO Surfaces through Chemisorption of Small Molecules Modification using Small Molecules Containing Carboxylic Acid Functionality Modification Using Phosphonic Acids and Other Chemisorbing Functionalities Conclusions Acknowledgments

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“…[15±19] Such a technique has recently been employed to fabricate ultra-thin layers of mono-functional conducting polymers at metal/polymer interfaces for OLED applications, with the specific aim of controlling interfacial charge injection. [18,19] In this paper we employ such a technique to fabricate thin interface layers of lithium-ion-doped dual-functional hole-transporting materials to control lithium ion composition at a nanostructured inorganic/organic semiconductor interface. We show that the lithium ions have a significant effect upon the interfacial charge recombination kinetics and thereby device function.…”

Section: Full Papermentioning

confidence: 99%

Interface Engineering for Solid‐State Dye‐Sensitized Nanocrystalline Solar Cells: The Use of Ion‐Solvating Hole‐Transporting Polymers

Haque¹,

Park

et al. 2004

Adv Funct Materials

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The control of interfacial charge transfer is central to the design of photovoltaic devices. This charge transfer is strongly dependent upon the local chemical environment at each interface. In this paper we report a methodology for the fabrication of a novel nanostructured multicomponent film, employing a dual‐function supramolecular organic semiconductor to allow molecular‐level control of the local chemical composition at a nanostructured inorganic/organic semiconductor heterojunction. The multicomponent film comprises a lithium ion doped dual‐functional hole‐transporting material (Li+–DFHTM), sandwiched between a dye‐sensitized nanocrystalline TiO2 film and a mono‐functional organic hole‐transporting material (MFHTM). The DFHTM consists of a conjugated organic semiconductor with ion supporting side chains, designed to allow both electronic and ionic charge transport properties. The Li+–DFHTM layers provide a new and versatile way to control the interface electrostatics, and consequently the charge transfer, at a nanostructured dye‐sensitized inorganic/organic semiconductor heterojunction.

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Ultrathin Self-Assembled Layers at the ITO Interface to Control Charge Injection and Electroluminescence Efficiency in Polymer Light-Emitting Diodes

Cited by 65 publications

References 0 publications

Using Self‐Assembling Dipole Molecules to Improve Hole Injection in Conjugated Polymers

Using Self‐Assembling Dipole Molecules to Improve Hole Injection in Conjugated Polymers

Modification of Transparent Conducting Oxide ( TCO ) Electrodes through Silanization and Chemisorption of Small Molecules

Interface Engineering for Solid‐State Dye‐Sensitized Nanocrystalline Solar Cells: The Use of Ion‐Solvating Hole‐Transporting Polymers

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