Physical vapor growth of centimeter-sized crystals of α-hexathiophene

Kloc, Ch.; Simpkins, P. G.; Siegrist, T.; Laudise, R.A.

doi:10.1016/s0022-0248(97)00370-9

Cited by 335 publications

(187 citation statements)

References 14 publications

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“…10,11 Pentacene crystals were investigated between room temperature and 400 K using an ENRAF/NONIUS CAD4 diffractometer ͑Cu K␣͒ with a homemade temperature control system, and additionally between 120 K and 413 K on the Swiss-Norwegian Beamline ͑SNBL, = 0.71 Å͒ at ESRF ͑Grenoble͒.…”

Section: Methodsmentioning

confidence: 99%

Large uniaxial negative thermal expansion in pentacene due to steric hindrance

et al. 2007

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The uniaxial negative thermal expansion in pentacene crystals along a is a particularity in the series of the oligoacenes and is exceptionally large for a crystalline solid. Full x-ray structure analysis from 120 to 413 K reveals that the dominant thermal motion is a libration of the rigid molecules about their long axes, modifying the intermolecular angle which describes the herringbone packing within the layers. This herringbone angle increases with temperature ͑by 0.3°-0.6°per 100 K͒ and causes an anisotropic rearrangement of the molecules within the layers, i.e., an expansion in the b direction and a distinct contraction along a. Additionally, a larger herringbone angle improves the cofacial overlap between adjacent, parallel molecules, and thus enhances the attractive van der Waals forces.

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Section: Methodsmentioning

confidence: 99%

Large uniaxial negative thermal expansion in pentacene due to steric hindrance

et al. 2007

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“…More recently, Kloc et al proposed a crystal-growth method in the vapor phase under a considerably high pressure of environmental gas (such as argon, helium, and hydrogen). [1,2] That method made accessible large single crystals of the molecular materials. For instance the authors made crystals of α-sexithiophene of ~1 cm in size both in closed and open systems.…”

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confidence: 99%

Improved Crystal‐Growth and Emission Gain‐Narrowing of Thiophene/Phenylene Co‐Oligomers

Ichikawa¹,

et al. 2003

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Large plate‐like single crystals of several millimeters to ∼ 1 cm in size of organic semiconducting materials are prepared via an improved crystal‐growth technique. The crystals (see Figure) exhibit self‐waveguided amplified spontaneous emission with a relatively small threshold resulting from the excellent optical properties of the crystals, such as high transparency and low light scattering.

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“…The OFETs have been fabricated using the parylene gate-dielectric technique that we used for fabrication of high-mobility OFETs based on free-standing organic molecular crystals [3]. The single crystals of rubrene have been grown from the vapor phase in a stream of ultra-pure hydrogen in a horizontal reactor [8]. Typically, thin flat crystals with dimensions of 1-3 mm in the (a,b) basal plane and 0.1-0.2 mm along the c-axis were used.…”

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confidence: 99%

Light-induced switching in back-gated organic transistors with built-in conduction channel

Podzorov

Pudalov

Gershenson

2004

Applied Physics Letters

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We report on observation of a light-induced switching of the conductance in the back-gated organic field-effect transistors (OFETs) with built-in conduction channel. In the studied devices, the built-in channel is formed owing to the self-sensitized photo-oxidation of rubrene surface. In the dark, the back gate controls the charge injection from metal contacts into the built-in channel: the high-current ON state corresponds to zero or negative back-gate voltage; the low-current OFF state -to a positive back-gate voltage that blocks the Schottky contacts. Illumination of the OFET in the OFF state with a short pulse of light switches the device into the ON state that persists in the dark for days. The OFF state can be restored by cycling the back gate voltage. The observed effect can be explained by screening of the back-gate electric field by the charges photo-generated in the bulk of organic semiconductor.* Electronic mail: podzorov@physics.rutgers.eduThe organic field effect transistors (OFETs) represent one of the key components in the organic electronics [1]. For many applications, the control of transistor operation with light would be desirable. However, until recently, the light-induced effects in OFETs were limited to observation of a photoconductivity response (see, e.g., [2]). One of the problems that hinder the study of the photo-induced processes in conventional thin-film transistors is a large concentration of structural defects in organic thin films that trap light-generated carriers and act as the recombination centers. Fabrication of the single-crystal OFETs [3,4,5,6,7], in which concentration of defects is significantly reduced, opens new opportunities for studies of light-induced effects in organic semiconductor devices.In this paper, we report on a novel light-induced effect in organic transistors: under illumination by a short pulse of light, the transistor switches from the low-current OFF state into the high-current ON state, which persists in the dark for days. This effect might be potentially interesting for light sensors and light-addressable memory applications.We observed this effect in an unconventional backgated OFET with a built-in conduction channel. The sketch of the back-gated OFET based on a single crystal of rubrene is shown in Fig. 1a. The OFETs have been fabricated using the parylene gate-dielectric technique that we used for fabrication of high-mobility OFETs based on free-standing organic molecular crystals [3]. The single crystals of rubrene have been grown from the vapor phase in a stream of ultra-pure hydrogen in a horizontal reactor [8]. Typically, thin flat crystals with dimensions of 1-3 mm in the (a,b) basal plane and 0.1-0.2 mm along the c-axis were used. The source/drain contacts and the gate electrode were formed on the opposite (a,b)-facets of the crystal, either by thermal evaporation of silver through a shadow mask or by painting with the colloidal graphite. These contacts are efficient injectors of p-type carriers in rubrene [3]. The injected carriers propagate...

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Physical vapor growth of centimeter-sized crystals of α-hexathiophene

Cited by 335 publications

References 14 publications

Large uniaxial negative thermal expansion in pentacene due to steric hindrance

Large uniaxial negative thermal expansion in pentacene due to steric hindrance

Improved Crystal‐Growth and Emission Gain‐Narrowing of Thiophene/Phenylene Co‐Oligomers

Light-induced switching in back-gated organic transistors with built-in conduction channel

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