Analysis of rectifying molecular thin films

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dc.contributor.advisor Ashwell, G. J. Miller, James R. 2016-08-25T08:46:12Z 2016-08-25T08:46:12Z 2005-09
dc.description.abstract The mercury-drop electrode technique, when used to measure the current/voltage characteristics of thin films of molecular rectifiers, is a useful, if awed method of analysis. Current/voltage plots taken from a number of samples confirm previous studies taken using the scanning tunnelling microscope (STM), but indicate significant levels of penetration of the mercury into the sample or stabilising monolayer. Quartz crystal microbalance (QCM) studies of the adsorption of 7,7,8,8°- tetracyanoquinodimethane (TCNQ) onto clean gold indicate small but significant adsorption, with possible formation of a salt, via conversion of TCNQ into the radical anion. This has implications for the results of previous experiments, which indicate alternative sources for the rectification observed from donor-bridge-acceptor systems, but also suggest use of the TCNQ radical anion as a electron donor when used to replace the counterion present in a number of self-assembled systems. Previous STM- based measurements confirming this latter suggestion are supported by mercury-drop studies. The results support conclusions previously drawn by a number of authors, removing much of the ambiguity surrounding their interpretation, whilst clarifying the adsorption characteristics of thiol-based molecules that contain a terminal TCNQ group, and to some extent, TCNQ itself. It is suggested that the mercury-drop technique should never be used in isolation to quantify rectification in monolayers of molecular rectifiers, but that it is suitable for use only i confirming and checking results from more established procedures. en_UK
dc.language.iso en en_UK
dc.publisher Cranfield University en_UK
dc.rights © Cranfield University, 2005. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder. en_UK
dc.title Analysis of rectifying molecular thin films en_UK
dc.type Thesis or dissertation en_UK
dc.type.qualificationlevel Doctoral en_UK
dc.type.qualificationname PhD en_UK

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