Diffusion of Triplet Excitons in Anthracene Crystals

Ern, V.; Avakian, P.; Merrifield, R. E.

doi:10.1103/physrev.148.862

Cited by 97 publications

(25 citation statements)

References 8 publications

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“…The cell angle of 60° secures that with small interference angles 99% or more of the excitation light can leave the fluorescence cell (at an angle close to the Brewster angle), and that the spatial period, resulting from interference of the incident beams with the beams, twice internally reflected, is very small because of the large interference angle of about 120° (with /0 = 351.1 nm and a refractive index n = 1.5 of the solution, 120° corresponds to a period e? = 135nm, and with (24) and Z) = 5 • 10 -6 cm 2 s" 1 to <3 = 1.08 • 10 6 s" 1 ; that means, equilibration of concentration by diffusion over this short period d is very fast and cannot cause any trouble in the determination of D). The DF of the region of maximum intersection of the two interfering beams was imaged by a toroidal mirror TM and a plane mirror M9 onto the slit SI (Fig.…”

Section: Measurement Of Time Dependence Of Dfmentioning

confidence: 98%

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Diffusion Coefficients of Aromatic Hydrocarbons in Their Lowest Triplet State: Anthracene in Hexane, Octane, Hexadecane, Perfluorohexane, and Methylcyclohexane; Pyrene and 9,10-Di-phenylanthracene in Hexane

Meyer

Nickel

1980

Zeitschrift Für Naturforschung A

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An experimental method is described which allows the determination of the diffusion coefficient D of an aromatic hydrocarbon in its lowest and metastable triplet state T\ with an absolute accuracy of ±5%. D was determined at 25 °C. With anthracene the temperature-dependence of D was measured from 0°C to 60°C in hexane and from 20°C to 89°C in hexadecane; it was found to be in good but not perfect agreement with the Stokes-Einstein equation. With the investigated systems, D of molecules in T\ is estimated to be at most 10% smaller than D of molecules in the ground state. No evidence for the formation of triplet excimers was found. Some applications of the method are proposed, and in this connection some questions concerning the kinetics of diffusion-controlled reactions of molecules in T\ and the existence of triplet excimers are discussed.

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Section: Measurement Of Time Dependence Of Dfmentioning

confidence: 98%

“…Independently from us Burkhart tried to measure diffusion coefficients of molecules in Tx [30 -32]. His method directly went on from the method of Ern, Avakian, and Merrifield [24].…”

Section: {Xt))xy[{c{xt))x] 2 = Vmin (6)mentioning

confidence: 99%

Diffusion Coefficients of Aromatic Hydrocarbons in Their Lowest Triplet State: Anthracene in Hexane, Octane, Hexadecane, Perfluorohexane, and Methylcyclohexane; Pyrene and 9,10-Di-phenylanthracene in Hexane

Meyer

Nickel

1980

Zeitschrift Für Naturforschung A

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“…It is then of foremost importance to develop both theoretical and experimental tools to improve our understanding of triplet exciton dynamics. Triplet migration has been a topic of intense research firstly in organic crystals [12] and aromatic hydrocarbons [17] and then more recently in amorphous organic semiconductors [18,19,20]. Along with theoretical work, it is essential to have reliable direct measurements of diffusion lengths to support both theory and device design.…”

Section: Introductionmentioning

confidence: 99%

Diffusion of triplet excitons in an operational organic light-emitting diode

et al. 2009

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Measurements of the diffusion length L for triplet excitons in small molecular-weight organic semiconductors are commonly carried out using a technique in which a phosphorescent-doped probe layer is set in the vicinity of a supposed exciton generation zone. However, analyses commonly used to retrieve L ignore microcavity effects that may induce a strong modulation of the emitted light as the position of the exciton probe is shifted. The present paper investigates in detail how this technique may be improved to obtain more accurate results for L. The example of 4,4'-bis(carbazol-9-yl)1,1'-biphenyl (CBP) is taken, for which a triplet diffusion length of L=16 ± 4 nm (at 3 mA/cm 2 ) is inferred from experiments. The influence of triplet-triplet annihilation, responsible for an apparent decrease of L at high current densities, is theoretically investigated, as well as the 'invasiveness' of the thin probe layer on the exciton distribution. The interplay of microcavity effects and direct recombinations is demonstrated experimentally with the archetypal trilayer structure [N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)]-4,4'-diaminobiphenyl (NPB)/CBP/ 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (named bathocuproine, BCP). It is shown that in this device holes do cross the NPB/CBP junction, without the assistance of electrons and despite the high energetic barrier imposed by the shift between the HOMO levels. The use of the variablethickness doped layer technique in this case is then discussed. Finally, some guidelines are given for improving the measure of the diffusion length of triplet excitons in operational OLEDs, applicable to virtually any small molecular-weight material.

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“…Under pulsed illumination, their radiative recombination leads to a photoluminescence (PL) signal that decays during the singlet lifetime. But in addition to this, creation of triplet excitons 8,9 can lead to a long-lived PL signal because of their long lifetime and their capability of fusing together to regenerate a singlet state that can radiatively recombine. 10 Most of the work in this field has concentrated on aromatic single crystals such as antracene, 8,9 tetracene, 10 and naphthalene.…”

mentioning

confidence: 98%

Triplet exciton dynamics in rubrene single crystals

2011

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The decay of the photoluminescence excited in rubrene single crystals by picosecond pulses is measured over 7 orders of magnitude and more than 4 time decades. We identify the typical decay dynamics due to triplet-triplet interaction. We show that singlet exciton fission and triplet fusion quantum yields in rubrene are both very large, and we directly determine a triplet exciton lifetime of 100 ± 20 μs, which explains the delayed buildup of a large photocurrent that has been reported earlier for low excitation densities.

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Diffusion of Triplet Excitons in Anthracene Crystals

Cited by 97 publications

References 8 publications

Diffusion Coefficients of Aromatic Hydrocarbons in Their Lowest Triplet State: Anthracene in Hexane, Octane, Hexadecane, Perfluorohexane, and Methylcyclohexane; Pyrene and 9,10-Di-phenylanthracene in Hexane

Diffusion Coefficients of Aromatic Hydrocarbons in Their Lowest Triplet State: Anthracene in Hexane, Octane, Hexadecane, Perfluorohexane, and Methylcyclohexane; Pyrene and 9,10-Di-phenylanthracene in Hexane

Diffusion of triplet excitons in an operational organic light-emitting diode

Triplet exciton dynamics in rubrene single crystals

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