A Possibility of 2-Dimensional Transport of Charged Carriers in Columnar Phases of Liquid Crystalline Semiconductors

Abstract

1,4,8,11,15,18,22,25-hexahexylphthalocyanine was studied on the carrier mobility characteristics by a Time-Of-Flight (TOF) technique. The compound exhibits an ambipolar nature of charge transport and the carrier mobilities for hole and electron were determined to be 0.3 and 0.2 cm² V⁻¹ s⁻¹ in the hexagonal disordered columnar (Col_hd ) mesophase and 0.3–1.4 and 0.4–0.5 cm² V⁻¹ s⁻¹ in the crystal. These values were obtained for poly-domain films. A possibility of 2-dimensional transport of carriers was discussed in terms of the molecular structure and orderings in both Col_hd and crystal phases.

Keywords:

• Organic electronics
• liquid crystalline semiconductor
• discotic liquid crystal
• phthalocyanine
• carrier mobility

Acknowledgements

This work was, in part, financially supported by a JSPS bilateral joint project (Japan-China). Y. Miyake thanks to a GCOE program in Osaka University.