Synthesis, Mesophase Behaviour and Charge Mobility of Phenyl-Thiophene Pentamers

Synthesis, Mesophase Behaviour and Charge Mobility of Phenyl-Thiophene Pentamers

Kuiper, S.

Picken, S.J. (promotor)
Dingemans, T.J. (promotor)
Jager, W.F. (promotor)

Applied Sciences

Chemical Engineering

2011-12-12

The performance of opto-electronic devices based on semi-conducting organic molecules, dependence on the molecular order of the semi-conducting molecules. To get high charge transportation through the material a high order of the material is needed. In our research we used liquid crystalline phases to get relative high order over large distances. A series of all-aromatic phenyl-thiophene pentamers and a series of alkoxy terminated phenyl-thiophene pentamers have been synthesized. The mesophase behaviour and the UV-vis absorption have been determined. In the nematic phase the molecules possess only orientational order. It was found that the orientational order, in the nematic phase of p-quinquephenyl, determined by wide angle x-ray diffraction is less, due to temperature dependent fluctuations of the director at a macroscopic scale. The exact temperature dependence of the orientational order was determined by birefringence measurements and could be fitted with the predicted temperature dependence of the orientational order by the Maier-Saupe model. In the smectic phases the molecules possess orientational order as well as positional order. The charge mobility was determined by time resolved microwave conductivity. In the nematic phase the charge mobility is dependent on the orientational order. Hardly any charge mobility could be observed in the higher ordered smectic phases, because the concentration of charges is reduced.

Liquid Crystal
Charge Mobility
Orientational Order
p-quinquephenyl
Phenyl-Thiophene Pentamers
Maier-Saupe Model

http://resolver.tudelft.nl/uuid:4e3aa6d8-8b54-4aba-ad5e-052244646ff7

2011-12-12

9789461860156

Institutional Repository

doctoral thesis

(c) 2011 Kuiper, S.