Efficient Electron Injection from a Bilayer Cathode Consisting of Aluminum and Alcohol‐/Water‐Soluble Conjugated Polymers

Wu, Hongbin; Huang, Fei; Mo, Yueqi; Yang, Wei; Wang, Deli; Peng, Junbiao; Cao, Yong

doi:10.1002/adma.200400067

Cited by 413 publications

(351 citation statements)

References 20 publications

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“…[6][7][8][9][10][11][12] A range of CPEs with different counterions (anion/cation) and backbones 13,14 have been synthesized in attempts to understand the role of the ions in the charge injection process. 15,16 The promising electronic properties of CPEs in combination with their solubility in polar solvents offer a unique route to the realization of high-performance polymer light-emitting diodes (PLEDs) without the use of reactive Ca or Ba cathodes.…”

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confidence: 99%

Conjugated Zwitterionic Polyelectrolyte as the Charge Injection Layer for High-Performance Polymer Light-Emitting Diodes

et al. 2010

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A new zwitterionic conjugated polyelectrolyte without free counterions has been used as an electron injection material in polymer light-emitting diodes. Both the efficiency and maximum brightness were considerably improved in comparison with standard Ca cathode devices. The devices showed very fast response times, indicating that the improved performance is, in addition to hole blocking, due to dipoles at the cathode interface, which facilitate electron injection.

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confidence: 99%

Conjugated Zwitterionic Polyelectrolyte as the Charge Injection Layer for High-Performance Polymer Light-Emitting Diodes

et al. 2010

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“…The use of CEs for interface engineering in (printed) polymer electronics hence is very attractive and much effort consequently has been invested into understanding the mechanisms for non-conjugated and conjugated electrolyte-based work function modification resulting in several different models recently being presented. [15,[17][18][19][20][21][22][23][24] One approach sets the work function modification by the electrolyte as a pure interface effect where one of the charged species can achieve a more intimate contact with the electrode surface by e.g. being more mobile than the counter charge.…”

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confidence: 99%

Regular Energetics at Conjugated Electrolyte/Electrode Modifier for Organic Electronics and their Implications on Design Rules

Bao

Liu

Wang

et al. 2015

Adv Materials Inter

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IntroductionPolymer-based electronic devices such as transistors, light emitting diodes and photovoltaic cells are considered to be an attractive technology with the potential advantages of high throughput, low manufacturing cost, light weight, and mechanical flexibility. [1][2][3] All such stacked devices contain several interfaces, e.g. electrode/organic and/or organic/organic, that significantly play a role in the device performance. Consequently much effort has been invested in tailoring electrodes using interlayers to optimize charge injection/extraction. [4][5][6][7][8][9][10][11] Recent reports have demonstrated that conjugated electrolytes (CEs) containing a -delocalized backbone and pendant ionic groups are very efficient charge injection/extraction interlayers for device operation, [12][13][14] as they can effectively tune the work function of metal electrodes. [12,15] Furthermore, the ionic groups render the CEs soluble in polar solvents, allowing the subsequent coating process of the organic layer with no damage to or intermixing with the underlying semiconducting polymer layer that typically is deposited with non-polar solvents. [16] Finally, since CEs feature -conjugated backbones they are reasonably efficient at transporting charge so that the relatively thick films obtained in printing processes could in theory be used without significant loss in device efficiency. The use of CEs for interface engineering in (printed) polymer electronics hence is very attractive and much effort consequently has been invested into understanding the mechanisms for non-conjugated and conjugated electrolyte-based work function modification resulting in several different models recently being presented. [15,[17][18][19][20][21][22][23][24] One approach sets the work function modification by the electrolyte as a pure interface effect where one of the charged species can achieve a more intimate contact with the electrode surface by e.g. being more mobile than the counter charge. [18] When the ions are located close to the interface, the Ion + and Ion -can interact with their respective induced image charge on the substrate, and since one of the ion species are more mobile, e.g. Ion + , those ions will move closer to the substrate and as a consequence form a "double dipole step" up-shifting the work function. [18] If the Ion -is more mobile, a double dipole step down-shifting the work function instead is formed. This effect only occurs at the interface and hence is film thickness independent. It also occurs independently of the substrate work function, but the size of the double dipole step is generally larger for metal electrodes than semiconductors (and ~negligible for insulator substrates).[18] For systems where both charges are equally mobile/immobile, e.g. zwitterion-based electrolytes, (partial) alignment of the ion-containing side chains through either interaction with the electrode at the interface or (bulk) realignment through an electric field will create dipole-induced potential steps. [21][22][23] Besides t...

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“…When incorporated into polymer light-emitting diodes ͑PLEDs͒, the LiF layer improves the device performance by increasing the electron attenuation length, by suppressing the interfacial reactions of the metal electrode with emissive layer during the cathode evaporation, and/or by reducing the barrier height of the electron injection through formation of a low work function interfacial layer at the cathode. 10,[13][14][15] The recent research using cationic systems [16][17][18] implies that anionic conjugated polyelectrolytes might offer several interesting opportunities for use in polymer-based optoelectronic devices. In light-emitting electrochemical cells ͑LECs͒, the mobile ions enable redox doping and the formation of ohmic contacts.…”

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Improved electron injection in polymer light-emitting diodes using anionic conjugated polyelectrolyte

Jin

Bazan

Heeger

et al. 2008

Applied Physics Letters

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We report improved performance in polymer light-emitting diodes incorporating conjugated polyelectrolytes as an electron injection layer (EIL). When we introduce water soluble conjugated polymers, poly[9,9′-bis(4-sulfonatobutyl)fluorene-co-alt-1,4-phenylene] (anionic PFP), between the aluminum (Al) cathode and emissive layer, the devices show an increased electroluminescence efficiency with a lowered turn-on voltage. We believe the mobile Na+ ions in the EIL layer directly influences the device efficiency by forming a low work function layer at the interface between the EIL and Al cathode, thereby facilitating the electron injection into the emissive layer.

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Efficient Electron Injection from a Bilayer Cathode Consisting of Aluminum and Alcohol‐/Water‐Soluble Conjugated Polymers

Cited by 413 publications

References 20 publications

Conjugated Zwitterionic Polyelectrolyte as the Charge Injection Layer for High-Performance Polymer Light-Emitting Diodes

Conjugated Zwitterionic Polyelectrolyte as the Charge Injection Layer for High-Performance Polymer Light-Emitting Diodes

Regular Energetics at Conjugated Electrolyte/Electrode Modifier for Organic Electronics and their Implications on Design Rules

Improved electron injection in polymer light-emitting diodes using anionic conjugated polyelectrolyte

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