Truxene discotic liquid crystals with two different ring substituents: synthesis, mesomorphism and high charged carrier mobility

Abstract

Discotic liquid crystals as a kind of promising organic electronic materials show self-assembly property as well as high charged carrier mobility. New truxene discogens, six 3,8,13-tri(alkoxy)-2,7,12-tri(methoxy)truxenes and two 3,8,13-tri(alkoxy)-2,7,12-tri(hydroxy)truxenes, have been synthesised with improved yields, were fully characterised and exhibited good thermal stability. The mesomorphism has been investigated by using polarised optical microscopy, differential scanning calorimetry and X-ray diffraction, and they exhibited ordered hexagonal columnar mesophase. More importantly, the charge carrier mobilities of 6d and 7f have been measured by using time-of-flight technique and 7f displayed hole drift mobility rate of 4.2 × 10⁻² cm² V⁻¹ s⁻¹ in the Col_ho phase and 0.1 cm² V⁻¹ s⁻¹ at a lower temperature M mesophase.

Keywords:

• mesophase semiconductors
• liquid crystal semiconductor
• discotic liquid crystal
• truxene
• hexagonal columnar mesophase
• hole mobility
• time-of-flight

Acknowledgements

This research was supported by the National Natural Science Foundation of China (Contract Nos 50973076, 51073112 and 51273133) and a NSFC-JSPS joint project.