Self-assembled tetraoctylammonium bromide as an electron-injection layer for cathode-independent high-efficiency polymer light-emitting diodes

2011 ◽  
Vol 21 (24) ◽  
pp. 8715 ◽  
Author(s):  
Sung-Nien Hsieh ◽  
Shih-Wei Hsiao ◽  
Tsan-Yao Chen ◽  
Chen-Yan Li ◽  
Chih-Hao Lee ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
Electron Injection ◽  
Light Emitting ◽  
Tetraoctylammonium Bromide ◽  
Electron Injection Layer ◽  
Polymer Light Emitting Diodes ◽  
Self Assembled

High Efficiency PPV-Based Polymer Light Emitting Diodes With Cs2CO3 Cathode

2008 ◽  
Vol 1115 ◽  
Author(s):  
Riikka Suhonen ◽  
Ralf Krause ◽  
Fryderyk Kozlowski ◽  
Wiebke Sarfert ◽  
Ralph Päetzold ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
Electron Injection ◽  
Electron Transport Layer ◽  
Strong Increase ◽  
Organic Layer ◽  
Charge Transfer Reaction ◽  
Light Emitting ◽  
Electron Injection Layer ◽  
Polymer Light Emitting Diodes

AbstractThe thin electron injection layers between the cathode and the light emitting polymer layer in polymer light emitting diodes (PLEDs) have been shown to have a big impact on the final device performance. Usually, in PLEDs low work function metals like Ba, Mg or Ca are used to reduce the energy barrier between the cathode and the polymer thus providing a better electron injection from the cathode. Also salts like LiF, NaF, Cs2CO3 and CsF have recently been shown to function as electron injection layers in light emitting devices. From these, especially caesium carbonate (Cs2CO3) results into high efficiency diodes both as a solution processed electron injection layer in PLEDs, as well as an n-dopant in the electron transport layer in vacuum deposited small molecule based OLEDs. The functional mechanism of Cs2CO3 as a pure interlayer is not yet fully understood. The proposed mechanisms include the n-doping of the organic layer with Cs2CO3, the thermal decomposition of Cs2CO3 and following formation of caesium metal or the formation of an n-doped CsO2 layer. In this study the phenomena resulting from the combination of a hole-dominant alkoxy-phenyl-substituted poly(phenylene vinylene) (PPV) based light emitting polymer with a highly efficient electron injection layer of Cs2CO3 in light emitting diodes has been investigated. As a result, diodes with about 35 % higher efficiency were achieved with PPV-Cs2CO3 structure in comparison to the traditional PPV-Ba structure. Additionally to the increased efficiency, also the lifetime of the Cs2CO3-diodes is comparable to the Ba-diodes implying that the long-term stability of the diodes is not affected by the optimized Cs2CO3-cathode. The strong increase in the electron injection of the Cs2CO3 diodes is apparently caused by a highly conductive, n-doped layer resulting from the charge transfer reaction between Cs2CO3 and PPV, where the magnitude of the reaction and resulting effects strongly depend on the amount of the applied Cs2CO3. The conclusion of the n-doped layer can be drawn from the LIV, impedance and photoluminescence measurements of the diodes with Ba and Cs2CO3 cathodes before, during and after electrical stressing.

Reduced molybdenum oxide as an efficient electron injection layer in polymer light-emitting diodes

2011 ◽  
Vol 98 (12) ◽  
pp. 123301 ◽  
Author(s):  
Maria Vasilopoulou ◽  
Leonidas C. Palilis ◽  
Dimitra G. Georgiadou ◽  
Panagiotis Argitis ◽  
Stella Kennou ◽  
...  
Keyword(s):  
Molybdenum Oxide ◽  
Light Emitting Diodes ◽  
Electron Injection ◽  
Light Emitting ◽  
Electron Injection Layer ◽  
Polymer Light Emitting Diodes

scholarly journals Mechanism study on highly efficient polymer light-emitting diodes utilizing double-layered alkali halide electron injection layer

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Qiaoli Niu ◽  
Jing Tong ◽  
Xiaomeng Duan ◽  
Haoran Zhang ◽  
Dexu Wang ◽  
...  
Keyword(s):  
Metal Cation ◽  
Alkali Halide ◽  
Light Emitting Diodes ◽  
Electron Injection ◽  
Main Role ◽  
Effective Strategy ◽  
Mechanism Study ◽  
Light Emitting ◽  
Electron Injection Layer ◽  
Polymer Light Emitting Diodes

AbstractEnhancing the injection of electron is an effective strategy to improve the performance of polymer light-emitting diodes (PLEDs). In this work, we reported a 286% improvement in current efficiency (CE) of PLEDs by using double-layered alkali halide electron injection layer (EIL) NaCl/LiF instead of LiF. A significant enhancement of electron injection was observed after inserting the NaCl layer. To understand the mechanism of such improvement, the devices with KBr/LiF and CsF/LiF as EILs were also investigated. Experimental results show that metal cation migrated under the effect of built-in electric field (Vbi), which plays the main role on the improvement of electron injection in PLEDs.

Enhanced Performance of Blue Polymer Light-Emitting Diodes by a Self-Assembled Thin Interlayer

2008 ◽  
Vol 8 (9) ◽  
pp. 4842-4845 ◽  
Author(s):  
Yun Ho Kim ◽  
Wonjoo Lee ◽  
Gangri Cai ◽  
Su Jin Baek ◽  
Sung-Hwan Han ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Sulfonic Acid ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Layer By Layer ◽  
Light Emitting ◽  
Polymer Light Emitting Diodes ◽  
Self Assembled ◽  
Thin Interlayer ◽  
Styrene Sulfonic Acid

High efficiency and long lifetime, blue polymer light-emitting diodes were obtained by adding a thin interlayer, which was fabricated by a layer-by-layer self-assembly technique between poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic acid) (PEDOT:PSS) hole transporting and emissive polymer layers in the device configuration of indium tin oxide (ITO)/PEDOT:PSS (65 nm)/interlayer (10∼30 nm)/emissive polymer (70 nm)/BaF2 (2 nm)/Ca (50 nm)/Al (300 nm). The interlayer, (PPV/PSS)n, consisted of self-assembled multilayers of the conjugated polymer, poly (p-phenylenevinylene) (PPV), and the polyelectrolyte, poly (styrene sulfonic acid) (PSS). Electroluminescence (EL) characteristics such as luminescence and current efficiency of the devices were enhanced by the addition of the interlayer. Furthermore, the devices with interlayer showed longer lifetime than those without interlayer. The maximum device performance was obtained from the device with (PPV/PSS)3 interlayer.

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