Carrier Transport in Calamitic Mesophases of Liquid Crystalline Photoconductor 2-Phenylnaphthalene Derivatives

Abstract

We have characterized carrier transport in mesophases of 2-phenyl-naphthalene derivatives by transient photocurrent measurements. In contrast to ionic conduction of isotropic and nematic (N) phase, electronic and ambipolar carrier transport was observed in smectic A (SmA), smectic B (SmB), and smectic E (SmE) phases. In particular, anomalous large mobilities on the order of 10⁻²cm²/Vs were obtained in SmE phase. Carrier mobilities in mesophases of 2-phenynaphthalene derivatives were increased stepwise corresponding to sophistication of molecular ordering from N to SmE. This indicated a dominant effect of molecular ordering on the carrier transport of calamitic mesophases.

Key Words:

• calamitic mesophase
• photoconductivity
• semiconductor
• smectic A
• smectic B
• smectic E