Long‐Lifetime Polymer Light‐Emitting Electrochemical Cells Fabricated with Crosslinked Hole‐Transport Layers

Shao, Yan; Gong, Xiong; Heeger, Alan J.; Liu, Meilin; Jen, Alex K.‐Y.

doi:10.1002/adma.200803698

Cited by 65 publications

(33 citation statements)

References 26 publications

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“…Therefore, to obtain reliable operative parameters of a LEC for a given ionic distribution, it is crucial to avoid ionic movement during the JL-V scans. [59][60][61][62] These experiments have shown that JL-Vs of fresh LECs are featureless, whereas after poling and fixing of the ions they resemble those of standard OLEDs. A thorough investigation of how LECs evolve from the initial state to the highly luminescent state was recently reported using JL-V analysis on dynamic LECs.…”

Section: Lecs: Mechanism Of Workmentioning

confidence: 92%

Luminescent Ionic Transition‐Metal Complexes for Light‐Emitting Electrochemical Cells

Costa¹,

Ortı́²,

Bolink³

et al. 2012

Angew Chem Int Ed

890

1,107

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Higher efficiency in the end-use of energy requires substantial progress in lighting concepts. All the technologies under development are based on solid-state electroluminescent materials and belong to the general area of solid-state lighting (SSL). The two main technologies being developed in SSL are light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs), but in recent years, light-emitting electrochemical cells (LECs) have emerged as an alternative option. The luminescent materials in LECs are either luminescent polymers together with ionic salts or ionic species, such as ionic transition-metal complexes (iTMCs). Cyclometalated complexes of Ir(III) are by far the most utilized class of iTMCs in LECs. Herein, we show how these complexes can be prepared and discuss their unique electronic, photophysical, and photochemical properties. Finally, the progress in the performance of iTMCs based LECs, in terms of turn-on time, stability, efficiency, and color is presented.

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Section: Lecs: Mechanism Of Workmentioning

confidence: 92%

Luminescent Ionic Transition‐Metal Complexes for Light‐Emitting Electrochemical Cells

Costa¹,

Ortı́²,

Bolink³

et al. 2012

Angew Chem Int Ed

890

1,107

View full text Add to dashboard Cite

show abstract

“…[50][51][52][53] In chemically stabilized LECs, with no added initiator compound, the cross-linking of the ions and/or ion-transport material is presumably initiated by the electrons/holes on the conjugated polymer. [39] This has the undesired consequence that the conjugation, i.e.…”

Section: Fig 3 Ftir Spectra Recorded On a {Poly-peo:metma/amps:dmpamentioning

confidence: 99%

On-demand photochemical stabilization of doping in light-emitting electrochemical cells

Tang

Edman

2011

Electrochimica Acta

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A highly functional p-n junction doping structure can be realized within a light-emitting electrochemical cell under applied voltage via ion redistribution and electrochemical doping. This doping structure will however dissipate when the formation voltage is removed due to the mobility of the dopant counter-ions. A number of concepts aimed at a spatial immobilization of the ions and the related stabilization of the doping structure have been presented, but they all suffer from long and poorly controlled stabilization periods and/or unpractical operational conditions. Here, we introduce a markedly fast and easy-to-control stabilization procedure involving the inclusion of a UV-sensitive photo-initiator compound into a carefully tuned active material in an light-emitting electrochemical cell device, and demonstrate that it is possible to cross-link the ions and stabilize the p-n junction doping via a short UV exposure step executed at room temperature.

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“…Sandwich LECs of low electrolyte content are of great importance, since they exhibit better long-term stability and have been the subject of many recent studies. 5,[16][17][18][19][20] Intuitively, one would expect that the LECs would behave more and more like a polymer light-emitting diode (PLED) as the electrolyte content is reduced. As such, the LECs would become a less efficient emitter under reverse bias due to less balanced charge injection.…”

mentioning

confidence: 99%

Decoupled luminance decay and voltage drift in polymer light-emitting electrochemical cells: Forward bias vs. reverse bias operation

Gao

AlTal

2014

Applied Physics Letters

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Sandwich polymer light-emitting electrochemical cells (LECs) with low electrolyte loading have been investigated. The LECs can be turned on to emit light at low voltages by applying either a forward- or reverse-bias current. The reverse operation, however, displays significantly higher luminance, frozen-junction behavior, and voltage instability. Moreover, the LECs display de-coupled luminance decay and voltage drift. Under forward-current operation, the luminance decreases for most of the test duration, while the operating voltage remains nearly unchanged. Under reverse-current operation, the luminance remains constant for over 200 h while the operating voltage more than doubles. The highly asymmetric device characteristics between forward and reverse operation can be explained by the different doping profiles created when the initial charge injection barriers are different. Under forward-current operation, the LEC film is predominantly p-doped. This leads to heavy luminescence quenching but a stable operating voltage. Under reverse operation, a predominately n-doped film is responsible for the higher luminance, frozen-junction behavior, and voltage drift. The anomalous device characteristics offer additional insights into the complex operating mechanism of LECs and the behaviours of a doped luminescent polymer.

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Long‐Lifetime Polymer Light‐Emitting Electrochemical Cells Fabricated with Crosslinked Hole‐Transport Layers

Cited by 65 publications

References 26 publications

Luminescent Ionic Transition‐Metal Complexes for Light‐Emitting Electrochemical Cells

Luminescent Ionic Transition‐Metal Complexes for Light‐Emitting Electrochemical Cells

On-demand photochemical stabilization of doping in light-emitting electrochemical cells

Decoupled luminance decay and voltage drift in polymer light-emitting electrochemical cells: Forward bias vs. reverse bias operation

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