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Proceedings Paper

TOF and TFT mobilities in polycrystalline thin films of liquid crystalline material
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Paper Abstract

We have fabricated polycrystalline thin films of liquid crystalline oligothiophene derivatives of ω, ω'-dioctylterthiophene (8-TTP-8) and ω, ω'-dihexylquarterthiophene (6-QTP-6). In order to evaluate carrier transport properties of the polycrystalline films in lateral and vertical orientations, we measured them by time-of-flight (TOF) experiments with sandwich type of liquid crystal cells and evaluating device performances of thin film transistors (TFTs) fabricated on SiO2/Si, respectively. Because of the liquid crystallinity, we could observe non-dispersive transient photocurrents in polycrystalline films of 8-TTP-8 in spite of thick sample of 16 μm, and determine hole mobility to be 0.3 cm2/Vs. Because of the same reason, in spin-coated thin film of 8-TTP-8, where 8-TTP-8 molecules sit perpendicular to the substrate, the field effect transistor (FET) mobility was successfully determined to be 0.1 cm2/Vs. In the same way, we have obtained the TOF and FET mobility for 6-QTP-6 to be 0.03 and 0.04 cm2/Vs, respectively. On the basis of the present results, we discuss the benefits of the liquid crystallinity in fabricating polycrystalline films as an organic semiconductor for device applications.

Paper Details

Date Published: 25 August 2008
PDF: 9 pages
Proc. SPIE 7054, Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics, 70540Y (25 August 2008); doi: 10.1117/12.795814
Show Author Affiliations
Hiroaki Iino, Tokyo Institute of Technology (Japan)
Core Research for Evolutional Science and Technology (Japan)
Jun-ichi Hanna, Tokyo Institute of Technology (Japan)
Core Research for Evolutional Science and Technology (Japan)


Published in SPIE Proceedings Vol. 7054:
Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics
Zhenan Bao; Iain McCulloch; Ruth Shinar, Editor(s)

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