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

Hiroaki Iino; Jun-ichi Hanna

doi:10.1117/12.795814

25 August 2008 TOF and TFT mobilities in polycrystalline thin films of liquid crystalline material

Hiroaki Iino, Jun-ichi Hanna

Proceedings Volume 7054, Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics; 70540Y (2008) https://doi.org/10.1117/12.795814
Event: Photonic Devices + Applications, 2008, San Diego, California, United States

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.

Citation Download Citation

Hiroaki Iino and Jun-ichi Hanna "TOF and TFT mobilities in polycrystalline thin films of liquid crystalline material", Proc. SPIE 7054, Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics, 70540Y (25 August 2008); https://doi.org/10.1117/12.795814

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