Large area liquid crystal monodomain field-effect transistors

Large area liquid crystal monodomain field-effect transistors

TNO Industrie en Techniek
van Breemen, A.J.J.M.
Herwig, P.T.
Chlon, C.H.T.
Sweelssen, J.
Schoo, H.F.M.
Setayesh, S.
Hardeman, W.M.
Martin, C.A.
de Leeuw, D.M.
Valeton, J.J.P.
Bastiaansen, C.W.M.
Broer, D.J.
Popa-Merticaru, A.R.
Meskers, S.C.J.

2006

Butyl, hexyl, and decyl derivatives of the liquid-crystalline organic semiconductor 5,5″-bis(5-alkyl-2-thienylethynyl)-2,2′:5′, 2″-terthiophene were synthesized and studied with respect to their structural, optical, and electrical properties. By means of an optimized thermal annealing scheme the hexyl and decyl compounds could be processed into self-assembled monodomain films of up to 150 mm in diameter. These were investigated with X-ray diffractometry, which revealed a clearly single-crystalline monoclinic morphology with lamellae parallel to the substrate. Within the lamellae the molecules were found to arrange with a tilt of about 50° with the rubbing direction of the polyimide alignment layer. The resulting, close side-to-side packing was confirmed by measurements of the UV/vis absorption, which showed a dichroic ratio of 19 and indicated H-aggregation. AFM analyses revealed self-affinity in the surface roughness of the monodomain. The compounds showed bipolar charge transport in TOF measurements, with hole mobilities reaching up to 0.02 cm2/Vs and maximum electron mobilities around 0.002 cm2/Vs. The hexyl derivative was processed into large-area monodomain top-gate field-effect transistors, which were stable for months and showed anisotropic hole mobilities of up to 0.02 cm2/Vs. Compared to multidomain bottom-gate transistors the monodomain formation allowed for a mobility increase by 1 order of magnitude.

Annealing
Crystalline materials
Liquid crystal displays
Semiconducting organic compounds
Synthesis (chemical)
X ray diffraction
Anisotropic hole mobilities
Self-affinity
Single-crystalline monoclinic morphology
UV/vis absorption
Field effect transistors
Polyimide
Thiophene derivative
Atomic force microscopy
Light absorption
Liquid crystal
Semiconductor
surface property

http://resolver.tudelft.nl/uuid:3df4408d-15e7-46f7-b1a8-c401cd52de40

https://doi.org/10.1021/ja055337l

239133

American Chemical Society

0002-7863

Journal of the American Chemical Society, 128 (128), 2336-2345

article