Molecular polaron states in polyacene crystals. Formation and transfer processes

Silinsh, E. A.; Klimkāns, Agris; Larsson, Sven; Čápek, V.

doi:10.1016/0301-0104(95)00151-d

Cited by 67 publications

(43 citation statements)

References 48 publications

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“…At low temperatures (T < 30 K), the carrier mobility levels off at values greater than 100 cm 2 =V s for Nph [16] and 10 4 cm 2 =V s for Pc [17]. At higher temperatures, a transition from band transport to hopping transport is observed in Nph [19], Pc, and other organic molecular crystals [20] consistent with some polaron models [7,8,20]. However, questions still remain regarding the nature of charge transport in organic molecular crystals [21].…”

supporting

confidence: 71%

“…However, dispersive transport with temperature independent exponents has been reported in polyvinylcarbazole [12], polyacetylene [44], and C 60 thin films [45], and has been attributed to intermolecular hopping processes [45] and nonactivated tunneling between sites with equivalent energies [15]. It is interesting to note that the nearly small molecular polaron model proposed by Silinsh et al [8] uses nonactivated tunneling to describe bandlike transport of polarons in polyacene crystals.…”

mentioning

confidence: 99%

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Picosecond Transient Photoconductivity in Functionalized Pentacene Molecular Crystals Probed by Terahertz Pulse Spectroscopy

et al. 2002

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We have measured transient photoconductivity in functionalized pentacene molecular crystals using ultrafast optical pump-terahertz probe techniques. The single crystal samples were excited using 800 nm, 100 fs pulses, and the change in transmission of time-delayed, subpicosecond terahertz pulses was used to probe the photoconducting state over a temperature range from 10 to 300 K. A subpicosecond rise in photoconductivity is observed, suggesting that mobile carriers are a primary photoexcitation. At times longer than 4 ps, a power-law decay is observed consistent with dispersive transport.

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supporting

confidence: 71%

mentioning

confidence: 99%

Picosecond Transient Photoconductivity in Functionalized Pentacene Molecular Crystals Probed by Terahertz Pulse Spectroscopy

et al. 2002

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“…17 The faster decay of the ͚ transient recorded on HMDS-treated substrates can be explained in terms of charge recombination processes. After direct ionization by the 193 nm laser whose photon energy ͑6.39 eV͒ exceeds the ionizing potential of the pentacene crystal ͑4.96 eV͒, 33 , the pair of positive and negative charges recombines with each other ͑geminate ion recombination͒. The free charge carriers are the main contributing factors to the observed values of ͚ , which is defined as charge escaped from recombination processes.…”

Section: ͑2͒mentioning

confidence: 98%

Electrodeless measurement of charge carrier mobility in pentacene by microwave and optical spectroscopy techniques

Saeki

Seki

Tagawa

2006

Journal of Applied Physics

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Photoinduced transient conductivity of pentacene thin films prepared by thermal vapor deposition is investigated using time-resolved microwave conductivity (TRMC) measurements, giving intrinsic charge carrier mobility in highly ordered structures without any electrode attached. The real and imaginary conductivity values are analyzed and compared with those predicted by molecular orbital calculations. The effects of substrate surface treatment by hexamethyldisilazane are discussed on the basis of kinetic traces of conductivity and morphology. A mobility of >0.7cm2∕Vs was obtained from the TRMC measurements and analysis of transient absorption spectra. The measurement of field-effect-transistor mobility in single-crystal domains requires not only complicated fabrication techniques but also many assumptions on the carrier channels, density, injection, etc. The combination of TRMC and transient optical spectroscopy provides an approach for addressing this issue. The present technique is applicable to a wide variety of organic semiconducting materials. Moreover, it is the only technique revealing the intrinsic potentials of mobility in materials that is supported by complete experimental and quantitative procedures not based on any assumptions.

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“…For example, the vibronic relaxation in pentacene causes a lowering of the positive polaron energy (also denoted as polaron binding energy) by approximately 0.2 eV. [21] The occurrence of an interface dipole at the PCPDTBT/PEDT:PSS interface (Figure 4) hints strongly at such a pinning, and the critical F value for pinning at positive polarons of PCPDTBT is about 4.7 eV below the vacuum level, that is, 0.4 eV above the VB onset.…”

Section: Energy-level Alignment At Electrodesmentioning

confidence: 99%

Electronic Properties of Interfaces between PCPDTBT and Prototypical Electrodes Studied by Photoemission Spectroscopy

et al. 2011

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We report on the electronic structure of poly[2,6-(4,4-bis- (2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT), a promising low-band-gap donor material for efficient bulk heterojunction organic solar cells. Electronic properties of interfaces formed between PCPDTBT and prototypical electrodes [Au, indium-tin-oxide and poly(ethylene-dioxythiophene): poly(styrenesulfonate)], obtained from X-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy, are evaluated. The formation of interface dipoles is observed, and their consequences for device performance are discussed. For the system PCPDTBT/Au chemical interactions occur, which may affect in particular the charge extraction at the corresponding interface.

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Molecular polaron states in polyacene crystals. Formation and transfer processes

Cited by 67 publications

References 48 publications

Picosecond Transient Photoconductivity in Functionalized Pentacene Molecular Crystals Probed by Terahertz Pulse Spectroscopy

Picosecond Transient Photoconductivity in Functionalized Pentacene Molecular Crystals Probed by Terahertz Pulse Spectroscopy

Electrodeless measurement of charge carrier mobility in pentacene by microwave and optical spectroscopy techniques

Electronic Properties of Interfaces between PCPDTBT and Prototypical Electrodes Studied by Photoemission Spectroscopy

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