Ultrafast carrier dynamics in pentacene, functionalized pentacene, tetracene, and rubrene single crystals

Ostroverkhova, Oksana; Cooke, David G.; Hegmann, Frank A.; Anthony, John E.; Podzorov, Vitaly; Gershenson, M. E.; Jurchescu, Oana D.; Palstra, Thomas

doi:10.1063/1.2193801

Cited by 112 publications

(107 citation statements)

References 22 publications

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“…These models agree well with measurements carried out on polymeric and polycrystalline small-molecule devices, where charges are localized and higher temperatures provide energy to overcome these barriers. Band-like transport is expected for high-quality single-crystal devices; indeed, band-like transport was reported in several different materials from time-of-flight (11)(12)(13), time-resolved terahertz pulse spectroscopy (14,15), and space-charge-limited current measurements (16). In an organic field-effect transistor (OFET) configuration, however, this type of behavior was observed in a very limited number of samples and only with specific dielectrics (17)(18)(19)(20)(21)(22)(23).…”

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confidence: 99%

Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps

Mei

Diemer

Niazi

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps

Mei

Diemer

Niazi

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…For perfectly ordered defect-free crystals, the Drude model based on band theory [10][11][12] is often used, where the charge mobility is determined from the mean relaxation time of the band states and the effective mass of the charge carriers. 13 The theory has been used to describe charge transport in highly purified organic crystals [14][15][16] such as pentacene [17][18][19] and rubrene. 20,21 However, the simple band-like picture does not take into account electron-phonon coupling.…”

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confidence: 99%

Charge Transport in Self-Assembled Semiconducting Organic Layers: Role of Dynamic and Static Disorder

et al. 2010

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Partial disorder is an inherent property of self-assembled organic semiconductors that complicates their rational design, because electronic structure, self-assembling properties, and stability all have to be accounted for simultaneously. Therefore, the understanding of charge transport mechanisms in these systems is still in its infancy. A theoretical study of charge transport in organic semiconductors was performed on self-assembled layers of [1]benzothieno[3,2-b]benzothiophene functionalized with alkyl side chains. Analysis showed that semiclassical dynamics misses static (on time scales of charge transport) disorder while the solution of the master equation combined with the high-temperature limit Marcus theory for charge transfer rates does not take into account molecular dynamic modes relaxing on a time scale of charge hopping. A comparison between predictions based on a perfectly ordered and a realistic crystal structure reveals the strong influence of static and dynamic disorder. The advantage of two-dimensional charge transporting materials over one-dimensional ones is clearly shown. The Marcus theory-based prediction of 0.1 cm 2 V -1 s -1 is in good agreement with our FET mobility of 0.22 cm 2 V -1 s -1, which is an order of magnitude lower than that reported in the literature [Ebata, H.; et al.

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“…Rubrene (C 42 H 28 ) in single crystal form has emerged as an important aromatic molecular solid, showing the highest field effect transistor (FET) mobility to date among organics (20 cm 2 =V s) [3]. In addition, several studies suggest that bandlike transport is operative [3][4][5][6]. Electronic properties in rubrene are, however, highly sensitive to both atmospheric environment as well as material treatment.…”

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confidence: 99%

“…In addition, several studies suggest that bandlike transport is operative [3][4][5][6]. Electronic properties in rubrene are, however, highly sensitive to both atmospheric environment as well as material treatment.…”

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Oxygen-Related Band Gap State in Single Crystal Rubrene

Mitrofanov¹,

Lang

Kloc³

et al. 2006

Phys. Rev. Lett.

115

113

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A molecular exciton signature is established and investigated under different ambient conditions in rubrene single crystals. An oxygen-related band gap state is found to form in the ambient atmosphere. This state acts as an acceptor center and assists in the fast dissociation of excitons, resulting in a higher dark and photoconductivity of oxidized rubrene. The band gap state produces a well-defined photoluminescence band at an energy 0.25 eV below the energy of the 0-0 molecular exciton transition. Twophoton excitation spectroscopy shows that the states are concentrated near the surface of naturally oxidized rubrene. DOI: 10.1103/PhysRevLett.97.166601 PACS numbers: 72.80.Le, 71.20.Rv, 71.35.ÿy Charge transport in organic molecular crystals is notably different from inorganic semiconductors. Despite a large number of investigations, understanding the fundamental processes governing charge transport remains a central issue for organic-based devices. In particular, the origin of band gap states and their effect on electronic and optical characteristics are both controversial and important questions [1,2]. Rubrene (C 42 H 28 ) in single crystal form has emerged as an important aromatic molecular solid, showing the highest field effect transistor (FET) mobility to date among organics (20 cm 2 =V s) [3]. In addition, several studies suggest that bandlike transport is operative [3][4][5][6]. Electronic properties in rubrene are, however, highly sensitive to both atmospheric environment as well as material treatment. As is true for inorganic semiconductors, device applications demand the understanding and control of such environmental factors, but the situation in rubrene is far from clear to date. Oxidation of organic crystals often results in modification of transport characteristics [7][8][9][10][11], and recent studies indicate that the presence of ambient oxygen also affects the conductivity of crystalline rubrene [12,13]. Furthermore, chemical analysis of naturally oxidized crystalline rubrene shows that the relative concentration of rubrene peroxide (C 42 H 28 O 2 ) can be as much as 1% at a depth of 50 nm [14], a length scale greater than a typical FET channel depth. Such a high impurity concentration will likely have a significant effect on charge transport, particularly if the impurity forms a band gap state.In this Letter, we demonstrate the formation of a band gap state in oxidized rubrene crystals and address the impact of the state on charge transport and exciton recombination. A spectral signature consistent with the molecular exciton model is established and investigated under different ambient conditions. A well-defined photoluminescence (PL) band at an energy lower than the highest exciton recombination transition energy develops in the spectra of oxidized rubrene. The PL band reflects an additional radiative recombination path through the oxygenrelated state in the band gap. The PL depth profile indicates that the oxygen-related band is emitted only from a surface region. Correlation between the ...

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Ultrafast carrier dynamics in pentacene, functionalized pentacene, tetracene, and rubrene single crystals

Cited by 112 publications

References 22 publications

Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps

Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps

Charge Transport in Self-Assembled Semiconducting Organic Layers: Role of Dynamic and Static Disorder

Oxygen-Related Band Gap State in Single Crystal Rubrene

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