Gas sensing applications of phthalocyanine thin films

Starke, T, 2000. Gas sensing applications of phthalocyanine thin films. PhD, Nottingham Trent University.

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Abstract

This thesis reports an investigation into the NO2 sensing properties of copper phthalocyanine (CuPc) thin films at room temperature in air. The gas sensing properties of the CuPc films were investigated using electrical conductivity and surface acoustic wave (SAW) sensing devices. Conductivity and SAW sensors were employed to detect changes of the film properties upon NO2 exposure in electrical conductivity and mass loading respectively.

Initially, the response of electrical conductivity and SAW sensors incorporating an untreated layer of CuPc was investigated. Laser illumination of the films during the sensing experiments was found to have a significant effect on the mass loading response but little effect on the change in electrical conductivity. From these experiments it was suggested that NO2 adsorption on CuPc may be dominated by two different mechanisms, surface adsorption and bulk diffusion. It was also suggested that a reduction of one of these components would lead to a more controllable response.

In order to minimise the effect of bulk diffusion, some of the CuPc films were doped with NO2 after deposition so filling the strongly bound bulk adsorption sites. In other devices, cooling of the CuPc layer in liquid nitrogen was used after deposition to change the surface structure in order to facilitate bulk diffusion. It was shown that these post-deposition treatment significantly changed the response characteristics of the CuPc film.

Response kinetics of the experiments were analysed using the Langmuir and Elovich adsorption models, a method was suggested to determine the concentration of NO2 within the first few minutes of exposure using the value for the maximum rate of current change. A good correlation between this value and the concentration was found.

Item Type:	Thesis
Creators:	Starke, T.
Date:	2000
ISBN:	9781369313147
Identifiers:	Number Type PQ10183022 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	28 Aug 2020 10:43
Last Modified:	21 Jun 2023 07:54
URI:	https://irep.ntu.ac.uk/id/eprint/40568

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