Charge transport anisotropy in a pentacene transistor with an underlying photo-alignment layer

Tatsuhiko Kawaguchi; Takehiro Okura; Yuuki Kondo; Ichiro Fujieda

doi:10.1117/12.873712

21 February 2011 Charge transport anisotropy in a pentacene transistor with an underlying photo-alignment layer

Tatsuhiko Kawaguchi, Takehiro Okura, Yuuki Kondo, Ichiro Fujieda

Proceedings Volume 7935, Organic Photonic Materials and Devices XIII; 79350H (2011) https://doi.org/10.1117/12.873712
Event: SPIE OPTO, 2011, San Francisco, California, United States

Abstract

Improving molecular packing of semiconductor materials in the vicinity of an insulating layer is of primary interest for efficient charge transport in an organic thin-film transistor. Self-assembled monolayers (SAMs) are often employed for this purpose. In other cases, a thin alignment layer is placed on a gate insulator in an attempt to order organic molecules along a specific direction. We fabricated bottom-gate, top-contact pentacene transistors with an underlying photo-alignment layer as follows. Azobenzene-polyamic acid was spin-coated on SiO₂ and was irradiating with linearly polarized ultraviolet light at various energy densities. The material was converted to polyimide by heating and a thin pentacene layer was evaporated on it. Finally, source and drain electrodes were formed by sputtering gold through a shadow mask. The transistors fabricated with the polarization perpendicular to the current direction in the channel showed higher field-effect mobility and the maximum value was 1.0cm²/Vs. This is close to the value reported for the conventional pentacene transistors having SAMs. The mobility decreased as the irradiation energy density increased. Hence, we attribute the anisotropy introduced by the photo-alignment layer to degradation in charge transport in the specific direction.

Citation Download Citation

Tatsuhiko Kawaguchi, Takehiro Okura, Yuuki Kondo, and Ichiro Fujieda "Charge transport anisotropy in a pentacene transistor with an underlying photo-alignment layer", Proc. SPIE 7935, Organic Photonic Materials and Devices XIII, 79350H (21 February 2011); https://doi.org/10.1117/12.873712

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