Recombination of singlet excitons with geminate pairs of charge carriers in conjugated polymers

Romanovskii, Yu. V.; Arkhipov, V. I.; Bäßler, H.

doi:10.1103/physrevb.64.033104

Cited by 31 publications

(17 citation statements)

References 24 publications

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“…In the case of geminate recombination one expects a linear dependence of the carrier density on the excitation fluence. The latter prediction holds of course as long as no excitonexciton or exciton-charge 30 annihilation processes become operative.…”

Section: Fig 4 MC Simulations Of Electron and A Hole (H ϩmentioning

confidence: 99%

Charge recombination in a poly(para-phenylene vinylene)-fullerene derivative composite film studied by transient, nonresonant, hole-burning spectroscopy

Offermans¹,

Meskers²,

Janssen³

2003

The Journal of Chemical Physics

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Transient, nonresonant, hole-burning spectroscopy has been used to study the charge recombination process in poly͓2-methoxy-5-͑3Ј,7Ј-dimethyloctyloxy͒-1-4-phenylene vinylene͔ ͑MDMO-PPV͒: methanofullerene ͑PCBM͒ composite films. The position and intensity of the spectral hole in the absorption band of MDMO-PPV have been monitored as a function of time in the 10 ns-10 s time range. A time-dependent redshift is observed. The intensity of the spectral hole decays with time according to a power law (ϰt Ϫ␣ ). The exponent ␣Ϸ0.5 is found to be nearly independent of the excitation fluence in the range 0.05-2 mJ/cm 2 . The depth of the spectral hole depends sublinearly on the excitation fluence ͑I͒ and can be described by (ϰ⌫ Ϫ␤ ) with ␤ϳ0.5. The time-dependent redshift and the power-law type time decay can be reproduced by numerical simulations. The Monte Carlo method is used to simulate the hopping dynamics of the photoinduced charges in a lattice of energetically disordered sites before they eventually recombine at the MDMO-PPV:PCBM interface. The results indicate that charge separation is assisted by disorder and that, in the 10 ns-10 s time range, the recombination rate is limited by the detrapping of the cationic charge carriers in MDMO-PPV.

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Section: Fig 4 MC Simulations Of Electron and A Hole (H ϩmentioning

confidence: 99%

Charge recombination in a poly(para-phenylene vinylene)-fullerene derivative composite film studied by transient, nonresonant, hole-burning spectroscopy

Offermans¹,

Meskers²,

Janssen³

2003

The Journal of Chemical Physics

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“…1 On the other hand, exciton quenching at charged traps might occur. 27 Energy of excitons could be transferred to the trapped charges via Forster mechanism, which is very efficient at a sufficiently large charge concentration and eventually results in the release of charges from the traps. With the high end-capper concentration, exciton quenching might harm EL emission from the end-capped PF2/6 devices under study.…”

Section: Resultsmentioning

confidence: 99%

Polymer Light‐emitting Diodes Based on End‐capped Poly[9,9‐di‐(2′‐ethylhexyl)fluorenyl‐2,7‐diyl]

Zhang¹

2010

Chin. J. Chem.

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We demonstrate polymer light-emitting diodes (LEDs) based on poly[9,9-di-(2'-ethylhexyl)fluorenyl-2,7-diyl] with end capper dimethylphenyl or N, N-bis(4-methylphenyl)-N-phenylamine. The introduction of end-capper groups increased the device luminance and efficiency, while greatly depressing the green emission. For the devices constructed of poly[9,9-di-(2'-ethylhexyl)fluorenyl-2,7-diyl] end capped with dimethylphenyl, the maximum luminance reached 381 cd/m 2 at 122 mA/cm 2 . The maximum external quantum efficiency was 0.16% at 117 mA/cm 2 , which is more than five times higher than that of the non-end-capped polymer LEDs. The electroluminescence (EL) maximum was at 485 nm, blue shifted by 52 nm with respect to that of the non-end-capped polyfluorene devices. It is proposed that efficient hole trapping at end capper and increased resistance of polyfluorene to oxidation are responsible for the improved device performance and color stability.

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“…[23,27] In fact, one of the other remaining important questions is exactly how electrical charge and excitation energy are transported along and between chains and on what timescale this occurs. [43,44] Charge and energy transfer affect a variety of processes such as triplet±triplet annihilation, [30,31,45] delayed fluorescence, [46] and exciton dissociation, [47,48] relaxation, and transport. [49] In addition, excitation energy can transfer to aggregate or excimer sites where an unsuitable relative orientation of adjacent interacting polymer chains may lead to only weak radiative coupling between the lowest excited state and the ground state, and consequently low emission efficiencies.…”

Section: Understanding Exciton Dynamicsmentioning

confidence: 99%

Fluorescence and Phosphorescence in Organic Materials

Köhler¹,

Wilson

Friend

2002

Adv. Eng. Mater.

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Progress reports are a new type of article in Advanced Engineering Materials, dealing with the hottest current topics, and providing readers with a critically selected overview of important progress in these fields. It is not intended that the articles be comprehensive, but rather insightful, selective, critical, opinionated, and even visionary. We have approached scientists we believe are at the very forefront of these fields to contribute the articles, which will appear on an annual basis. The article below describes the latest advances in fluorescence and phosphorescence in organic materials.

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Recombination of singlet excitons with geminate pairs of charge carriers in conjugated polymers

Cited by 31 publications

References 24 publications

Charge recombination in a poly(para-phenylene vinylene)-fullerene derivative composite film studied by transient, nonresonant, hole-burning spectroscopy

Charge recombination in a poly(para-phenylene vinylene)-fullerene derivative composite film studied by transient, nonresonant, hole-burning spectroscopy

Polymer Light‐emitting Diodes Based on End‐capped Poly[9,9‐di‐(2′‐ethylhexyl)fluorenyl‐2,7‐diyl]

Fluorescence and Phosphorescence in Organic Materials

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