Poly(<i>p</i>-phenylenevinylene) light-emitting diodes: Enhanced electroluminescent efficiency through charge carrier confinement

Brown, Adam R.; Bradley, Donal D. C.; Burroughes, J. H.; Friend, Richard H.; Greenham, Neil C.; Burn, Paul L.; Holmes, Andrew B.; Kraft, Arno

doi:10.1063/1.108094

Cited by 702 publications

(278 citation statements)

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“…The applied voltage must be high enough to overcome the energy barriers for the injection of charge carriers. Typically, the potential difference is much greater than the thermal voltage, V 1 (orV k BT /ê 26 mV) [2]. Therefore, we prescribe the…”

Section: Asymptotic Analysismentioning

confidence: 99%

“…A standard device configuration consists of a transparent anode, typically indium tin oxide, an organic semiconducting polymer film that is 10-1000 nm thick and a metallic cathode [2][3][4][5]. An applied voltage drives the injection of electrons through the cathode, and electron vacancies, or holes, through the anode into the organic thin film, where they diffuse and migrate, or drift, towards the oppositely charged electrode.…”

Section: Introductionmentioning

confidence: 99%

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Asymptotic analysis of double-carrier, space-charge-limited transport in organic light-emitting diodes

2013

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We analyse electron and hole transport in organic light-emitting diodes (OLEDs) via the drift-diffusion equations. We focus on space-charge-limited transport, in which rapid variations in charge carrier density occur near the injecting electrodes, and in which the electric field is highly non-uniform. This motivates our application of singular asymptotic analysis to the drift-diffusion equations. In the absence of electronhole recombination, our analysis reveals three regions within the OLED: (i) 'space-charge layers' near each electrode whose widthλ s is much smaller than the device widthL, wherein carrier densities decay rapidly and the electric field is intense; (ii) a 'bulk' region whose width is on the scale ofL, where carrier densities are small; and (iii) intermediate regions bridging (i) and (ii). Our analysis shows that the currentĴ scales asĴ ∝εμV 2 /L 2λ s , whereV is the applied voltage,ε is the permittivity andμ is the electric mobility, in contrast to the familiar diffusionfree scalingĴ ∝εμV 2 /L 3 . Thus, diffusion is seen to lead to a large O(L/λ s ) increase in current. Finally, we derive an asymptotic recombination-voltage relation for a kinetically limited OLED, in which charge recombination occurs on a much longer time scale than diffusion and drift.

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Section: Asymptotic Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Asymptotic analysis of double-carrier, space-charge-limited transport in organic light-emitting diodes

2013

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“…In addition, 2,5-disubstituted-1,3,4-oxadiazole derivatives have also been used as electron conducting and hole blocking (ECHB) materials for electron deficient and good electron transport properties of oxadiazole rings. 4 The most common synthetic approach to 1,3,4-oxadiazoles involves cyclodehydration of 1,2-diacylhydrazines 3 (Scheme 1). Typically, this reaction is carried out by using SOCl 2 ,…”

mentioning

confidence: 99%

(PhIO)_nMediated Annulations of Aromatic Aldehyde N-Acylhydrazones for the Synthesis of 1,3,4-Oxadiazoles

Shang¹,

Ha²,

Tao³

et al. 2013

Bulletin of the Korean Chemical Society

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“…Electronic mail: kusumiitd@gmail.com. governs 10,11 the charge transport either 12,13 by drift of charge carriers under the influence of traps, distributed in energy space, called trap model or by temperature and field dependent mobility models. The former mechanism dominates at higher temperature and the latter at lower temperatures ͑Ͻ200 K͒.…”

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confidence: 99%

Effect of CdSe quantum dots on hole transport in poly(3-hexylthiophene) thin films

Kumari

Chand

Kumar

et al. 2008

Applied Physics Letters

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This letter demonstrates the effect of cadmium selenide ͑CdSe͒ quantum dots on hole transport in poly͑3-hexylthiophene͒ ͑P3HT͒ thin films. Current-voltage characteristics of P3HT and P3HT:CdSe thin films have been studied in the temperature range of 288-85 K, in hole only device configurations, i.e., indium tin oxide ͑ITO͒/poly͑ethylene-dioxthiophene͒:polystyrenesulphonate ͑PEDOT:PSS͒/P3HT/Au and ITO/PEDOT:PSS/P3HT:CdSe/ Au. The incorporation of CdSe quantum dots in P3HT results in the enhancement in hole current and switches the transport from dual conduction mechanism, viz., trap and mobility models to only trap model. This is attributed to the reduction in characteristic trap energy from 60 to 32 meV and trap density from 2.5 ϫ 10 18 to 1.7ϫ 10 18 cm −3 . © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2955524͔Polymer-fullerene interpenetrating bulk heterojunctions ͑BHJs͒ are currently the most efficient approach in organic photovoltaics. Power conversion efficiency ϳ6% has already been realized 1 in poly ͑3-hexylthiophene͒: ͓6,6͔-phenyl-C61 butyric acid methyl ester ͑P3HT:PCBM͒ BHJs. However, there is a strong need to search for innovative ways to enhance further the efficiency and stability of these polymer solar cells. One of the promising approaches is the incorporation of different 2-5 inorganic nanoparticles such as titanium dioxide ͑TiO 2 ͒, cadmium telluride ͑CdTe͒, cadmium selenide telluride ͑CdSeTe͒, zinc oxide ͑ZnO͒, etc., into host conducting polymers such as poly͓2-methoxy, 4-͑2-ethylhexoxy͒-1,3-phenylene vinylene͔ ͑MEH-PPV͒ and P3HT. Encouraging results are already available in literature on the preparation of solar cells using polymer P3HT and CdSe nanostructures. [6][7][8] To improve further the performance of P3HT:CdSe based polymer solar cells it is essential to understand their device physics especially the role of nanoparticles/quantum dots on charge transport properties of the composite matrix. In this letter we have investigated the effect of dispersion of CdSe quantum dots on hole transport in P3HT thin films. Current-voltage ͑J-V͒ characteristics of P3HT thin films were studied in hole only device configuration, i.e., indium tin oxide ͑ITO͒/poly͑ethylene-dioxythiophene͒:polystyrenesulphonate ͑PEDOT:PSS͒/P3HT/Au in the temperature range of 288-85 K, without and with dispersion of CdSe quantum dots of size ϳ5 nm. It has been found here that the incorporation of CdSe quantum dots in P3HT switches its hole transport from a dual conduction mechanism, viz., trap and mobility models to only trap model. This finding explicitly reveals the pivotal role played by CdSe quantum dots in governing charge transport of P3HT:CdSe composite films that would prove beneficial in the development of improved solar cells based on organicinorganic composites.Samples for both pure P3HT and P3HT:CdSe composite films were prepared under identical conditions in hole only device configurations, i.e., ITO ͑ ϳ 4.8 eV͒/PEDOT:PSS ͑80 nm͒ / P3HT͑ϳ180nm͒ / Au ͑ ϳ 5.2 eV͒ and ITO ͑ ϳ 4.8 eV͒/PEDOT:PSS ͑80 nm͒/P3HT:...

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Poly(p-phenylenevinylene) light-emitting diodes: Enhanced electroluminescent efficiency through charge carrier confinement

Abstract: Articles you may be interested inTemperature-dependent electroluminescence in poly [2-methoxy -5(2′-ethylhexyloxy )-pphenylenevinylene ] light-emitting diode

Cited by 702 publications

References 18 publications

Asymptotic analysis of double-carrier, space-charge-limited transport in organic light-emitting diodes

Asymptotic analysis of double-carrier, space-charge-limited transport in organic light-emitting diodes

(PhIO)_nMediated Annulations of Aromatic Aldehyde N-Acylhydrazones for the Synthesis of 1,3,4-Oxadiazoles

Effect of CdSe quantum dots on hole transport in poly(3-hexylthiophene) thin films

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Poly(p-phenylenevinylene) light-emitting diodes: Enhanced electroluminescent efficiency through charge carrier confinement

Abstract: Articles you may be interested inTemperature-dependent electroluminescence in poly [2-methoxy -5(2′-ethylhexyloxy )-pphenylenevinylene ] light-emitting diode

Cited by 702 publications

References 18 publications

Asymptotic analysis of double-carrier, space-charge-limited transport in organic light-emitting diodes

Asymptotic analysis of double-carrier, space-charge-limited transport in organic light-emitting diodes

(PhIO)nMediated Annulations of Aromatic Aldehyde N-Acylhydrazones for the Synthesis of 1,3,4-Oxadiazoles

Effect of CdSe quantum dots on hole transport in poly(3-hexylthiophene) thin films

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(PhIO)_nMediated Annulations of Aromatic Aldehyde N-Acylhydrazones for the Synthesis of 1,3,4-Oxadiazoles