Carrier dynamics in α-octithiophene solids: Comparison of the transient photoconductivity and excited-state absorption in single-crystal and polycrystalline film

Moses, D.; Wang, J.; Dogariu, Arthur; Fichou, Denis; Videlot, C.

doi:10.1103/physrevb.59.7715

Cited by 7 publications

(4 citation statements)

References 13 publications

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“…Comparative transient PC studies have been carried out recently by Moses et al on a-8T single crystals and polycrystalline thin ®lms. 140 The essential purpose of these comparative experiments is to study the intrinsic properties of photoexcitation and transport in model molecular crystal systems and to determine the role of structural defects. Picosecond transient PC measurements over a wide range of temperatures (10±300 K) demonstrate that the dependence of photocurrent on light intensity and electric ®eld in the single crystal a-8T is radically different from that in vacuumdeposited polycrystalline ®lms (Fig.…”

Section: Photoconductivity and Photovoltaic Cellsmentioning

confidence: 99%

“…Reported values of photoluminescence (PL) ef®ciency for a-6T polycrystalline thin ®lms are in the range 10 24 to 10 22 % 163,164 although ef®ciencies up to 9% have been recently measured on a-4T, a-6T and a-8T single crystals. 140 In the solid state, the intense 1A g A1B u allowed transition of a-6T splits into two levels (Davydov splitting estimated in the range 10 000±15 000 cm 21 ), the fundamental transition having an energy of 2.43 eV. 165 Introduction of alkylated substituents on the a-6T backbone modi®es intermolecular distances and strongly affects optical spectra and transport properties.…”

Section: Light-emitting Diodes (Leds) and Laser Crystalsmentioning

confidence: 99%

See 1 more Smart Citation

Structural order in conjugated oligothiophenes and its implications on opto-electronic devices

Fichou¹

2000

J. Mater. Chem.

511

372

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Section: Photoconductivity and Photovoltaic Cellsmentioning

confidence: 99%

Section: Light-emitting Diodes (Leds) and Laser Crystalsmentioning

confidence: 99%

Structural order in conjugated oligothiophenes and its implications on opto-electronic devices

Fichou¹

2000

J. Mater. Chem.

511

372

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“…34 More direct measurements of the transient photoconductivity using contact-biased samples and a fast oscilloscope are also useful for understanding the nature of photoexcitations and charge transport in organic materials. [36][37][38][39] Some preliminary results on contacted, voltage-biased, functionalized pentacene crystals are also given.…”

Section: Introductionmentioning

confidence: 98%

Picosecond transient photoconductivity in organic molecular crystals

Hegmann

Ostroverkhova

Gao

et al. 2004

Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII

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We examine ultrafast photoconductivity in functionalized pentacene single crystals using optical-pump terahertz-probe techniques. The 0.5 ps rise time observed in the photoconductive transients, which is limited by the response time of the terahertz pulse setup, suggests that mobile charge carriers are a primary photoexcitation. The peak of the photoconductive signal increases as the temperature decreases due to higher carrier mobilities at lower temperatures. A lower limit for the carrier mobility of 1.6 cm 2 /Vs at 10 K and 0.2 cm 2 /Vs at room temperature is obtained. We further show that the absorption edge near the pump excitation wavelength of 800 nm remains temperature independent, and is therefore not a contributing factor in our observation of larger transient signals at lower temperatures. After an initial fast decay, a power-law decay is observed in the tail of the transient response from 2 to 600 ps. The dependence of the photoconductive response on the pump fluence and the electric field amplitude of the terahertz pulse are examined. Finally, we show some preliminary results of transient photocurrent measurements on contact-biased samples using a fast oscilloscope with a system rise time of about 50 ps.

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“…Exciton dynamics in -hexathiophene [26] and tetracene [27] single crystals have been recently studied using ultrafast pump-probe techniques, but these experiments are not sensitive to carrier transport. Transient photoconductivity has been measured in pentacene [7] and -octithiophene [28] single crystals with 10 ns and 25 ps time resolution, respectively, but noncontact techniques with better time resolution are desirable.…”

mentioning

confidence: 99%

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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Carrier dynamics in α-octithiophene solids: Comparison of the transient photoconductivity and excited-state absorption in single-crystal and polycrystalline film

Cited by 7 publications

References 13 publications

Structural order in conjugated oligothiophenes and its implications on opto-electronic devices

Structural order in conjugated oligothiophenes and its implications on opto-electronic devices

Picosecond transient photoconductivity in organic molecular crystals

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

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